I wouldn't agonize too much over timbre-matching the rear speakers. I would definitely get the qs8's for the surrounds and just install whatever in-ceiling speaker floats your boat for the rears. Vann's often has good sales on the Mirage Omnicans, which I kind of like the looks of. I have some of their inwalls in my kitchen and they sound pretty good, although not as good as a freestanding Axiom \:\)

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