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I'm thinking of the VP150 for center and the QS8's of course.
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I agree go bigger if you can, but M22's with a good sub is an awesome combo.
Regarding center channel, I know Cat says he did not have a favourable experience with M2 as a center, but for me in my room I found the M2 to be a very good upgrade to the VP150 as a center channel. Nobody is right or wrong here, but I did want to point out you should consider a vertical center if you can, no matter what speakers you end up purchasing. It's a really good option that most people just never consider.
Oh yeah, go with QS8's, they are just awesome IMHO.