Compiz is not just for Gnome, many people run it in KDE as well. Granted there are Gnome elements in it, but some are actually being stripped out.. and it really doesn't matter what libraries an app uses...
The problem, as you stated, is that Compiz requires 3d acceleration that can compete with other 3D things... of course that's rare and with Compiz-Fusion 0.6 it's actually very stable and can work with other GL apps nicely (it's been running for 2 weeks straight on my Gentoo box)... and when it doesn't you can set Compiz to turn off compositing for that app.
The bigger problem is that the new design of the MD UI will shift allot of the alpha-blending stuff to the new KDE WM, as stated by Paul... this will effectively kill all other WM options for LinuxMCE... this shift i all heartedly disagree with...
Edit: I forgot to mention that I did install Cedega and Crossover Office (two Wine variants) on my Core and they worked just fine.