Well I use Bryston(4B-ST) with my B & W CDMs, with hardwood floors in a 15x22, and I am pleased with the sound. I believe the Bryston ST series where known for being bright with great bass. I like highs, so this is right up my proverbial alley. The SST series has improved sonics all over I believe.
If you like high volume and you have alot of space to fill, your gonna need some juice. Not to mention B & Ws really like to be fed some watts. Bi wiring does a lot as well, but that is another thread.
Seeing that you listen to very little 2 channel, you may be better served by disregarding all my previous suggestions. All the Amps I mentioned are very fine machines indeed, but, those mentioned tend to be more 2 channel oriented.
I think the Sunfire 400x7 should not be disregarded so easily. Dont get me wrong I love Bryston, and "peddle" them here on a regular basis. Your using N802(front) HTM1(center) and N804(surround) in a 5 channel setup, right? With the 7 channel Sunfire you could use 4 channels for your N802s, essentailly biamped, and the other three channel for the center and surrounds.
Ultimately it isnt the watts, its your ears. Get what sounds best, if you have dealers in your area I would suggest you get them to let you have an in home tryout.