Personally, I'm not a big fan of in-ceiling speakers, they just can't give you the same experience as it was intended. Also, not sure your going to find another mfg's. in-ceiling speaker with the same tonel/timber characteristics. You'll still get sound, but it won't be as good as what the Q-series would give you.
In reality, the left/right surrounds should be to the left/right of the listeners. Have you considered wall mounting some Q's off to either side, you can get a color that looks nice with your trim?
Another option might be the architecture series in-wall series from Axiom. Although they arent totally flat to the wall/ceiling, they are much lower profile than the other speakers in the Axiom lineup..
It was important to me that all my speakers matched in quality and color.
good luck.
