I am looking into changing my M7D's for Canton CD 310 F's. However, seeing as my primary listening is movies the conclusion I think I am coming to is that I may be better with my bioploe M7D's for the diffusion. I have been searching on the whole bipole, dipole and monopole thing and it seems many people prefer monopole / direct radiating for the surround back. So I may even try the Canton's in the middle of my back wall for the 7.1 surround back channels. My questions are: a) would this work OK seeing as my sofa is right up against the back wall? b) could I be jeapordising the quality of the surround soundfield and steering by having two brands of speakers? c) would I be better sticking with 4 missions or 4 cantons?