I think some of this depends upon which daw you are using… and if it supports MPE, and how well it’s implemented.
I’ve used Live 11 and Bitwig (and quite a time back Cubase) and didn’t really have any (technical) issues. (though as below, I dont use it that much !)
as (current versions of ) Bitwig and Live have MPE support you can indeed transpose notes, as they attach the modulations (X/Y/Z) to the note.
I personally would avoid using MPE+, not only is it more data, but Bitwig/Live has not been developed with these in mind… so Im pretty sure they will not handle it properly.
(and indeed, I know that you have to take out some dubious messages to make it work at all)
now this will reduce the ‘accuracy’ of the data, taking it from 14 bit to 7bit, but given form factor of Osmose, I personally don’t think this is an issue (due to relatively short travel, compared to continuum) - and Ive been fine with this in the past.
that said, as Ive stated many times here, and elsewhere…
personally I rarely bother with midi/mpe, I much prefer to record audio.
yes, I know WHY you might want to record midi, I dont deny the advantages, but FOR ME, currently the hassle outweighs the advantages.
so I only use MPE to control mpe enabled synths (like Madrona Labs Aalto), and even those, I still record the audio!
why don’t I do mpe recording?
even normal midi note editing is pretty tedious…
but, even with a decent MPE implementation in your daw,
there is just so much data from MPE its beyond tedious, so I never will edit the mpe.
also in my mind there is a fundamental issue…
the advantage of midi (over audio) is the ability to change the sound / preset later.
in my experience that does not work too well for expressive controllers.
why?
because your (expressive) playing is tightly linked to what you are hearing, you are ‘performing’ in a feedback loop - so you modulations wont transfer well to another preset.
put another way, if I played on a regular keyboard , and then changed the preset.
whilst the notes might work well on a different preset, Id almost certainly have to change the modulation lanes.
but , this is a very personal choice… its not that I cannot record MPE, its I choose not too.
(I say personal, however, I know a lot of players with different expressive controllers, and almost all of them, for the most part, record audio, rather than midi/mpe)
of course, if you are working in a pro studio with clients, and so need recall, re-playability.
you might not have the luxury of this choice… time is money 
anyway, the tech is fine, in my experience … dont worry too much about data rates etc.
it works, many of us have been using expressive controllers for quite a few years, both before and after mpe introduction…
and frankly, my Osmose doesnt spit any more data than my Eigenharp, likely much less 
Sure…. Every digital synth is essentially a “softsynth in a box”… but a lot of times, the box is worth having (Osmose, Hydrasynth, Montage, many others).
