I have two M200's I use for music with a pair of the entry level Maggies, but they're power hungry and not very efficient. (but still great!)

I don't think I'd use just an M200 for just the center. (unless you've got something similarly power hungry like a Martin Logan center?)

I think there's a lot of goodness in having the same speakers & amps for left, center, right & surrounds. So for movies/TV I just drive five NHT Super Zeros with a 7100 with the other two channels driving a pair of 10" subs I built.