Have you tried the gen~ reverbs, the gigaverb is pretty good, as are other 'native' max reverbs. I have not been able to get other vst reverbs (tal reverb, ambience) to work in 64 or 32 bit mode - this is in Max 7
yeah, gen is good. :) it's helpful for me to work against target sound sometimes, hear what it's doing and try adjustments of code to match. imo the hard part about a lot of reverb is figuring the meta parameter changes. and there are certain aspects of( almost all of) apple's au that screw up in kinda cool ways really. :)
for some reason i thought they had released source of all of them as examples at some point, but i couldn't find it.
also stacking reverbs with different design/ sound/parameter emphasis. :)