Finally got a chance to try a few calculations in this spreadsheet with my setup (B100s driving a pair of KEF LS50 Metas from my listening position based on speaker placement but not even including subwoofer), and only need somewhere from 7-16 watts (depending on impedance I put in, since KEF rates it 8ohms with minimum 3.5ohms) to hit peak 90dB at my listening position. This is way less than the B100 puts out. Again, this is not even factoring the fact that I have an SVS SB-3000 providing the slam--which means all of my real-world testing was lower wattage still than any of these calculations for the measured sound levels.
Why are people so worried about power? 23-52 watts would be needed if I were even willing to listen with 95dB peaks, which I am not. I was test-listening an orchestral piece yesterday (which is the very loudest material I like listening to), and set the volume to a place where I was already fairly uncomfortable with the loudness, and after an hour of playback, only hit a peak of 92dB (with an average of about 72dB), which translates to 11-26 watts depending on impedance.
At this rate, B200s would be $600 worth of overkill for my setup.
-Ed