I seem to understand the concept, but it is still not very clear. So if I'm loading the "MOTIF XF Performances for MONTAGE" or "MONTAGE Expanded" on MODX and I choose the library file, then it will not overwrite my user content. But if I load the user file, then it will overwrite my user created performances, waveforms and arps?

That is correct!

Your User Performances, Waveforms and Arpeggios that occupy your USER Bank were either loaded there from a File (in which case overwriting is not a big deal, you can restore it when you want it, at anytime) or the data currently there you just created and STORED it to a User location... in which case save a User file... so that overwriting it is no big deal.

There are 640 possible User Performance location, 2048 possible Waveforms, 256 User Arps, etc., etc. You can review what is currently in your current User Bank by viewing the following Data Folders:
Press [UTILITY] > “Contents” > “Data Utility”
FOLDERS: Arp, Live Set, Motion Seq, Performance and Waveform
(The others, Library, Song, and Pattern are independent of the User Bank).

The User Bank is your working RAM area. It is where you can put data when you want to work on/Edit it... make changes to it, add new Performances, new Waveforms, create new Arpeggios, configure Live Sets, create Motion Sequences... if you do, you should immediately make a File .X8U User File and keep it on your USB stick.

These 5 User data Folders (listed above) are overwritten whenever you Load a User File .X8U

If you Load the “Motif XF Performance” file or you Load the “Montage Expanded” File directed to the USER BANK, it will replace the data in the 5 Folders (Arp, Live Set, Motion Seq, Performance and Waveform) with the data programmed by the author of the User File you loaded.

The Arps will be identified as User Arp
The Live Sets will be identified as User Live Sets
The Motion Seqs will be identified as User Motion Seqs
The Performances will be identified as User Performances
The Waveforms will be identified as User Waveforms

All User data of these types are overwritten and replaced by the User data contained in a File .X8U

The way that you can create a Library File is you save the current User Bank as a Library File. It is a “SAVE AS...” routine, like on a computer.
The way that you Save a “user word document” in a more universally readable format, you might SAVE AS... PDF.

Saving your User data as a Library creates a specific file format .X8L that can “burn” your data to Flash Memory when you LOAD it. This file includes instructions that “burns” the data into memory.

This makes it impervious to being overwritten. This makes your Arps, your Live Sets, your Motion Seqs, your Performances and your Waveforms as permanent as the factory Arps, Live Set, Motion Seqs, Performances and Waveforms. They will be in your memory until you specifically DELETE them (or initialize your entire instrument).

The Library data is the equivalent of a User Bank that has been made a (semi)-permanent part of your MODX.
You can create 8 Libraries. One at a time.

That’s the background.
When you load something, like the files you mention, directly to a LIBRARY.... You would do so because you want to hear it, and make specific selections from it. Say you only like 100 Performances from the data you Loaded... why keep all the others in memory. This is specifically an issue when it comes to Waveforms (which can be quite large in size).

You load them all to the Library
Decide which ones you want to keep — you simply select the Performance by name
You mark them and do a “Library Import”
This copies the selected Performances from the Library and makes an autonomous copy in your User memory. Remember this is your work area. It also copies whatever Arps and Waveforms your selections require.

Significantly, the “Library Import” allows you to move data from ROM (FLASH) to the RAM (work area) without overwriting any thing in the work area. Remember Loading a User File overwrites the existing User data.

“Library Import” DOES NOT. It allows you to *add* data from various Libraries and allows you to combine them into a new USER BANK... which, if you’ve been getting this, can then be SAVED AS... a new installable Library.

A Library is data that has been “burned” into permanent memory.
A catalog is made so that you are able to reference it via the Search engine whenever you need.

A MODX Factory Preset ‘knows’ where to ‘look’ to find any Waveform... your Library data will be cataloged in a similar fashion as the factory data.
In any AWM2 Part, the Waveform will be located in the Preset Bank, the User Bank, or one of 8 Library Banks.

Your factory Presets are always there... they are burned in permanently at the Yamaha factory
Your Library data will always be there... they are burned into (semi)-permanent memory in your studio room.

It seems to be more clear now, but...

The User Bank is your working RAM area.

The only problem I have with this statement is that *technically* RAM is supposed to be volatile memory. In a computer, the contents of RAM are lost when it is rebooted or powered down. This is, of course, not the case with the User Bank of MODX. So I assume that both the User and Library banks are some sort of flash. Maybe one is solid state, and the other eMMC?

Getting away from the underlying technology:

User memory can be edited randomly. You can delete a single Performance, you can add a single Performance, you can change a single Performance. You can also clear the entire User memory area if you want.

Library memory can only be written to in its entirety for each library slot and can only be erased in its entirety for each library slot. You can't edit or erase single Performances inside a library. You can either erase (delete) the whole library slot or load an entire library slot with contents.

Both will keep their contents after you power down.

The edit buffer represents a scratchpad for altering any Performance. When you load a Performance, you can start changing it (no matter if it came from a Library, User, or Preset location). These changes are made in the edit buffer. Anything in the edit buffer as in any changes can be [STORE]'d (saved) into the User memory area.

Since the edit buffer does not survive power-downs (also is overwritten if you change to a different Performance) - you must [STORE] the contents if you want to ensure they are kept.

Maybe this is a stupid question, but is it safe to have my backup files on the same USB stick I use to install these expansion packs and MODX firmware updates. Does it make sense to save the MODX backups on a separate USB drive, or keep it on Google drive or somewhere?

Firmware update instructions say to only have the firmware install on the USB drive and nothing else. Advice would say not to include backups there. I personally don't follow this advice - but do as I say not as I do ...

You should save your MODX backups in as many places as you can. I've advocated saving them on a USB stick, hard disk, and some cloud location (google drive is OK - or just email to yourself or both). It's bad to lose data if you've worked long hours to create it. Backup redundancy is insurance.

... and if an sound expansion set has a user file - the utility is if you want to start editing these without taking 2 steps (load to library first, then import to user). The utility is also if you want to slim down the set and choose your keepers. Loading straight to the user area will again skip that Library import step. In order not to mix your existing user content with the expansion contents, you're going to want to delete the user area no matter which way you go. The steps would be to backup your user area first - then you can load the user file and start editing or pruning down the pack. Instead of backing up the user area, initializing the user area (*), loading the pack to a library slot(*), importing from library to user area(*), deleting the library(*), then start editing or pruning down the pack.

Those (*) steps get to be skipped if you start with a user file. Therefore, I'm happy to have the choice for the sound expansion content that offers the user file(s) in addition to the library file(s)

The only problem I have with this statement is that *technically* RAM is supposed to be volatile memory. In a computer, the contents of RAM are lost when it is rebooted or powered down. This is, of course, not the case with the User Bank of MODX. So I assume that both the User and Library banks are some sort of flash. Maybe one is solid state, and the other eMMC?

While certainly some forms of RAM are volatile, it is not a prerequisite for RAM. This is the expensive type that allows data to remain between power cycles. (And you wouldn’t want it any other way)

The word “vulnerable” may help... the data in the USER Bank is vulnerable to being overwritten.
Loading another .X8U file will replace the current User Bank data.
The Library ROM in invulnerable, it cannot be overwritten by any simple Load operation (exception: restoring a complete BACKUP .X8A) In other words, loading a second Library File will automatically occupy Library slot 2. Loading a third will automatically occupy Library slot 3, and so on. Until you fill all 8 Library slots.

Now, you can go through an installed Library, *select* the the Performances you like from each, and use the “Library Import” function to copy them to the USER (RAM) work area. In this fashion, Library by Library, you can assemble your own custom Bank - in RAM.

Why this is useful... when a commercially available Library comes out, you, typically, are not going to get a full set of 640 Performances... the number of Performances can vary greatly depending on what is being offered. A Library that consists of one meticulously sampled instrument like (Bosendorfer Imperial Grand, Chick Corea’s Mark V) they each provide about 16 Performances. All Performances use the same exact set of samples. Then there are Libraries that provide a variety of instruments, and a variety of instrument sample sets, and still there are Libraries that use internal Waveforms and provide no addition Waveforms/Samples — these can contain 100 or more Performances... it can vary greatly, here. There is really no benefit to keeping separate Libraries — other than how they appear in your Search fields. Most searches are done by instrument, not Library name (or that’s how it seems once you start amassing lots of Performances). If I’m looking for an acoustic piano, or an electric piano, I know the Bosendorfer and the Chick Corea Mark V will be included in the listing by category.

A Library with just 16 Performances is fine, right up until you have 8 different Libraries installed. You get the Library memory full message.
This is when consolidating (streamlining) your data becomes essential. Each LIBRARY at max can house 640 Performances. You can move data using this “Library Import” routine.

Assemble your Performances in the User Bank — importing ‘adds to’ the data already in the “work area”
Then you can SAVE AS... a new custom Library File .X8L
Now you can DELETE the installed Libraries
Finally, Load (install) your custom, streamlined Library file — installing it to one Library (ROM) slot.