Sure it's OK because it's hidden. Well, aren't there already many extension of Sysex ? MMC, Time Code, Alternate tuning, Sample Standard (which, too bad no one uses) to name a few and also hidden for 99.9% of users? What is it with this 'I hate Sysex'. MIDI-CI is probably the most complex and most instrument resource consuming extension of Sysex ever. Yes, it does have very interesting features, but so do have the existing ones. (Going to print a T-Shirt now with 'I love SysEx') :-)
Aren't MMC and MTC more for controlling transport and linking with non-musical instrument applications?
I've dabbled with SysEx and would love to not have to think in hex again if at all possible. The new spec would allow that to be a reality, so I'm pretty happy to hear the news. I've not delved into exactly how it will change how MIDI will be transmitted, but it would be nice for a larger bandwidth to be implemented, considering the time taken for larger SysEx transmissions currently, especially with SysEx sample TX's.
With regards to resource consumption, I'd imagine that could be taken care of by ARM processors and the like that are powering consumer mobile devices currently. With virtual instruments running on phones now, it may not be an issue for developers who are all ready utilising the mobile platform.
Overall it's an exciting time for the future of MIDI instruments and how they integrate for the benefit of the electronic musician (think the end of being part musician/part coder!)
With regards to the tee-shirt, perhaps for a little fun change the capitalisation to SySex?