I’m not at all sure about your reasoning about why MOXF (2013) data doesn’t load to Motif XF (2010), unless you know something I don’t. It’s true, but I’m not at all sure that your guess at the reason is accurate.

The MODX (2018) will certainly be able to load any data made for MONTAGE (2016)...
The MONTAGE cannot Load MODX proprietary Files.

Something to do with the directionality of Time (and Product ID)
What Limit are you referring to?
Is there MODX data that is not available to both? I know of no specific MODX exclusive data.

If you are thinking about developing content for these Motion Control Engine synthesizers it would be wise to develop it on the top-of-the-line (MONTAGE), this way the MODX series will be able to read it, as well.

Hello Bad Mister and thanks for your reply.
Assuming I'm not a Yamaha engineer working in its R&D dept, I try to think about "raw" specs and put myself some questions. As far as I know, MOXF and Motif XF have the same WaveROM content, the same Voice structure, the same synth engine in short, thus they might exchange their data back and forth without any limitations. But this doesn't happen.
Same said for MODX and Montage, and again this doen't happen due to a mysterious obstacle.

I'd be very interested into loading MODX Performances into Montage because they were programmed thinking about the 4 Parts SSS limit, in other words, MODX Performances are more "polyphony wise".
Making a comparison between MODX and Montage the difference in number of arpeggios immediately stands out, among other minor differences (Insert Effects, for instance).
I hope not this is the only reason to keep MODX data incompatible with Montage.

Hello Bad Mister and thanks for your reply.
Assuming I'm not a Yamaha engineer working in its R&D dept, I try to think about "raw" specs and put myself some questions. As far as I know, MOXF and Motif XF have the same WaveROM content, the same Voice structure, the same synth engine in short, thus they might exchange their data back and forth without any limitations. But this doesn't happen.
Same said for MODX and Montage, and again this doen't happen due to a mysterious obstacle.

I understand. Often it is not immediately clear why one product does what it does and another does not. They are different products with different names and different Product IDs. That has more to do with it than what you can guess at by looking at “‘raw’ specs”. They don’t share the same engine, they share a similar engine, and what you're guessing at falls under the Phrase: the devil’s in the details.

Where possible, the most recent product can typically read the older product (a matter of perspective) when there is shared technology (and this is the case hear)
There are going to times or situations where the less expensive product does not have the same exact feature set, and because of this data compatibility going the other direction is simply not feasible.

Sometimes it is exactly because they share some technology and functions that trying to supersede the file incompatibility can result in unexpected results. If there were a big demand or requirement to make MODX data compatible with the MONTAGE, I’m sure it could be done but thinking they because they are similar means they should be the same, well... it isn’t always that easy.

I'd be very interested into loading MODX Performances into Montage because they were programmed thinking about the 4 Parts SSS limit, in other words, MODX Performances are more "polyphony wise".
Making a comparison between MODX and Montage the difference in number of arpeggios immediately stands out, among other minor differences (Insert Effects, for instance).
I hope not this is the only reason to keep MODX data incompatible with Montage.

MODX Performances = MONTAGE Performances.
What “polyphony wise” Performances are you speaking of?
MONTAGE Performances = MODX Performances

Please see this post for details:
Maximum Parts Playable

Hello Bad Mister,

Thanks again for your explanation.
Simply, for "poyhony wise " Performances I mean those MODX Performances limited up to 4 Parts that if loaded in the Montage would not engage its polyphony in full.
Maybe I might be wrong, but if a Performance is designed in advance to take advantage of a smaller polyphony, on a more powerful instrument (i.e. Montage) it will charge less the synth engine. Again, if MODX Performances sound already full, on the Montage, adding new Parts, will be sounding more and more full.
Last but not least, I also hoped that MODX had different Performances from the Montage, in order i can load them in the latter...

MODX Performances are 16 parts, same as Montage. 8 can be controlled by the MODX keyboard, the remaining 8 can be controlled by an external source (e.g. controller). I think you refer to fact that only 4 parts can utilize SSS vs 8 parts SSS in Montage? Thats not polyphony per se, but it is a difference.. A different thread describes the reason.

I don't think either polyphony or the 4/8 SSS are related to why a MODX file can't be loaded into a Montage. Perhaps Melas will create a conversion tool, though I don't think I'd own both machines to ever find out.

HI badMister, and congratulations on bringing in an exciting new product with an amazing price point, feature set and legacy! AND weight >..<
I thought the OP was getting at if there were any new sounds in the MODX that we Montage users could benefit by - fruits of the latest Yamaha programing geniuses-
However you say, "In fact, all of the 2143 MODX Factory Performances are identical to the first 2143 Performances in MONTAGE" - so I guess that's not the issue.
What was confusing me was your saying "The MONTAGE cannot Load MODX proprietary Files." (what, other than Performances could that refer to?)
Thanks.

One can over think this, but they are different Products which means there is a different Product ID... This means each has its own System Exclusive messages. This can be different enough to cause issues with system settings... there is more to the file than just Performance data.

This is why MONTAGE CONNECT (.X7B) cannot be used in place of MODX CONNECT (.X8B), nor vice versa.
And naturally the BACKUP FILEs (.X7A, .X8A) would be completely incompatible.

Things could change. Currently, the MODX is to MONTAGE, as MOXF was to Motif XF.
The more recent product is a lighter version with some compatibility with its older more powerful sibling.

The MONTAGE remains a firmware version or two ahead of the MODX.

An engineer could tell you what’s different and why; I can tell you that the .X8L and .X8U Files are currently, not recognized by the MONTAGE.
However, the MODX can translate/convert MONTAGE .X7U and .X7L Files.
The User File contains your Utility setups - these can be a cause of issues between products of different series.

The MONTAGE would need to be taught to translate/convert MODX File data... if/when a need to do so arises, I imagine that can happen.
The translation would ensure that all issues were addressed... as far as I know, that doesn’t exist quite yet.