It's completely understandable that the W100 sounds different when it's out in your room. It was designed with the wall's proximity in mind. Once it's in the wall, though, it will probably still sound a bit difference simply because it's not in the same location as your M22s.
Is this your first center channel? I prefer listening to music with the center channel off. I think the phantom center created by the front left and right speakers sounds much better. When the center channel is in the mix, it seems to rob some breadth from the soundstage.
