I have found that for the majority of feature-film DVD's, the center channel is the most power hungry channel. I've found the same to be true for television viewing using 2-channel analog inputs with PLII-C. Perhaps Soundhound can offer a comment on this from a production mixing point of view.

Cetainly 100W is not shabby for a center channel and may be plenty. My thought is that the center channel might make better use of power headroom than the rear, unless your rear speaker(s) are significantly less efficient and/or much farther from your listening position(s) than the center channel.

Other thoughts, anyone?