I'm very fond of my M200's, each of which drives a Paradigm Studio/60. In my case, I selected them because I already had a five-channel amp (the Model 750) and needed two more channels. Some folks have gone with the "super-stack" of M200's (seven separate power supplies, redundancy in case one channel fails), while many others have simply picked up the 770 (one box instead of seven, one more cord instead of seven). Both routes are very safe bets. If I were doing it from scratch, I'd probably go with the 770 just for convenience (or possibly the 755 and a pair of M200's).

Oh, and Keta's question may be somewhat rhetorical, but at HE2005 the 990 was paired up with a 770.