The number of Destinations is not mentioned because, it becomes irrelevant at a certain point. For example, you can map 128 stereo samples horizontally across the keyboard - or you can map the 128 stereo samples vertically to play at different velocities... those are the theoretical limits of Key Bank construction in the Motif XF, for example. If you've worked with mapping samples you realize that the extreme (theoretical) limits are not how the feature is going to be used in an actual case. It is always somewhere less than the extreme limit that is the most useful.

It's more a matter of practical "use case". You are beginning to see just how deep the Montage engine is - and why it was described as "alien technology" in some of the pre-leaked commentary... If you're into programming, get ready to have some serious fun! If you just into playing (and are not a programmer) there will be plenty of sounds to share and experience... at least that is what we are anticipating.

If you understand the XS/XF - MOXF, they have a six Control Set Source/Destination arrangement, then imagine Montage has sixteen Source/Destination arrangements per Part, plus instead of just a DEPTH setting that allowed linear change via a two-dimensional range and direction setting... In Montage the "DEPTH" setting has been expanded to include the kind of detail that allows each Motion Control Sequence Step to be as simple or as complex as your imagination can wander. And the fact that the Steps can be linked to tempo, and use UNIT MULTIPLY to greatly expand their usefulness while referencing tempo. At 100% sixteen Steps could be sixteenth notes, but because you can multiple/divide the value at which it references tempo, you can expand or contract the length of a Step.
50% UNIT MULTIPLY would be double time. The same sequence takes half the time to occur
200% UNIT MULTIPLY would be cut time (half time). The same sequence takes twice as long to occur.
Out to 6400%... 64 times as long to occur...

In Motif/MOXF you could pan one thing left to right, while the other thing panned right to left on a single controller movement. Basically, as you observed, on a linear curve as they bypass each other... You can have these two items pass each other several times, crisis crossing multiple times, with the same single controller gesture.

Imagine "panning" applied using the following Curves - to pan two things so they each moved in opposite formation (the application of "DEPTH" setting, is now mind-boggling).

The Motion is set polar opposite for each - so they would be passing each other according to the sequence... Apply this to any parameter... Volume, for example, effects, filter cutoff, etc., etc.,

Playing or listening to the Montage in anything but glorious stereo would be criminal, as you will miss out on some of the movement. 🙂

I've started a weekly series of articles on "scuba diving" Montage... one of things revealed is that you can control the "Depth" direction/range, etc., at the Control Assignment screen within the PART and/or at the link to the Super Knob. Your decision about what gets linked where will have to do with your personal preference as to how that particular Knob or Control behaves... How far you want it to move to get the result. You have influence at both ends... its really cool. You have to relax at some point when programming this because you have 8 Assignable Knobs per PART. So ganging things together on a single Control, while it certainly can be done, often you simply have another Knob available.

As I said - I can't even begin to imagine what the motion seqs can achieve using this, but I'm pretty sure that even a simple filter cutoff assigned to modwheel using the "AM" curve type (pictured above) can provide an entirely new level of dynamic expression. I can't wait to try this out.