I'm having great difficulty "chasing" your posts. I think you're posting lots of related topics and deleting some. Hopefully you'll get the hang of the forum soon.

Here's a response I had for a related message that I believe you may have deleted:

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It's easiest to answer the discrepancy between your playing and what the arp is doing because that part of your description makes sense and I follow.

One issue you have is with your manual playing and what velocity you're able to achieve. Due to multi-sampling, effects, filters, etc. many sounds will sound different (different character, timbre) if they are triggered with higher velocities vs. lower ones. If you prefer the sound with higher velocities - you may find you're not able to "manually" (directly) achieve the velocities which puts the sound in the preferred range. There are ways to adjust this. Globally, there are velocity curves. You can try setting these and see if your ability to play at higher velocities is improved. You can even set the velocity to a fixed single value. 127 will be the highest value and would represent constantly playing at maximum velocity. This may be exactly what you want - or maybe 100 would do it. You can experiment.

The other option is to modify the bass Part so the velocity response to your playing is adjusted. You can set a velocity offset which says "if the player directly hits a velocity of X, then I'm going to interpret this as a velocity of X+offset". That's one way - there are more options for changing the velocity when you are editing the part. And you can perhaps achieve a result that is still dynamic (not fixed) - but biases the response closer to achieve higher velocities without your having to pound the keyboard as much.

As far as gate time and popping - gate time describes how staccato the notes are played. Not velocity. Not volume. Just note length of how long the piano key is pushed down to sound the note. Note length is a combination of sound and silence. The most legato note (or slurred) runs one note into the next. It's all sound and no silence. This would be the maximum gate time (no silence between notes). When you adjust the gate time, you are adjusting how much of a note is sound and how much is silence. You would accomplish this in direct playing by playing either more staccato or more legato.

I'm not sure exactly what you're trying to accomplish with the ARP so I can't necessarily help with the second part. I can infer. Note that gate time has a dial on the instrument - so you can real-time adjust this as the ARP is playing.

You can change the knob function to [ARPMS] in order to allow for a knob to represent gate time.

When I create my own arp I can reduce the gate time (for the whole pattern) to make the bass sound "pop" a bit more - I thought I saw a demo with Blake where he varied the gate times across the ARP pattern to allow some notes to be longer and some shorter? Is this correct?

The factory Bass Arps were played and/or assembled by a musician. You should be able to do exactly what they have done...
You can have the Arp playback with the original velocity used or you can influence how much velocity is applied by having it interpret your Key On Velocity. And as you know, the Arp Play FX can be applied to it.

You can, using the Arp Play FX, apply offsets to the Velocity of an ARP Phrase, you can also offset the Gate Time (duration of the notes in the Arp Phrase) you do not have to apply it to ALL Parts, you can apply these Arp Play FX on an individual Part basis.
Select the Part with the Bass
Press [EDIT] > “Arpeggio” > “Common” > the right side of the screen has your Arp offsets to Velocity, Gate Time, etc., etc.

If you record your own Bass line to a Pattern Scene, for example, — you have a similar set of offsets called Play FX, that allow you to apply them to your recorded data.
From the “Play/Rec” > “Pattern” screen > tap “Edit/Job” > “Play FX” > you have “Play FX 1” which is Quantize and Swing Quantize...
And “Play FX 2” which are your Velocity, Gate Time, and Shifting offsets

Most Drum Kit sounds are configured to ignore changes in GATE TIME (duration) just FYI. You can set drum response on a per Key basis.

Among the Play FX you will find a Velocity Offset for Arp Phrase data and different one for Pattern Track data.
If you want to apply change to just the Bass do so, if you make all musical notes the same length (Gate) it may sound a bit unnatural or a bit unusual, Your mileage will vary per the music it is applied to...