I'm now to sure but I think Mark is referring to the cabinet structure. From what I have read it's better to have all three channels the same, since each cabinet has it's own characteristics. Cabinet effects can be reduced or eliminated with a baffle wall. But then again what do I know I used different cabinet for the center...
On the subject of the surrounds I had the RS7's before going with the RS62's. Now in my honest opinion the RS62's sound better, they offer a more even sound. I've seen where some people say the new R series have a different sound than the older R series but I can't hear any miss matching. I have a second pair of RS62's in the works, for the back channels, so it should sound even better. We seem to both like the sound of the horns behind the SMX screen so I feel comfortable suggesting the new Klipsch to you.
Honestly if you go with good speakers, that blend well I don't think you can go wrong. Calibration really helped my sound, I can't wait to get it done by a pro. Once I have all the toys in I'm going to have the room modeled, and professionally calibrated.
Those are nice amps, as we talked they put out some wattage. I too will beef up my amp soon enough, at this time I'm thinking 300x7 from Adcom or 200x7 from B&K. Bi amping the fronts, I'll need amps for the surrounds as well. When it's all said an done I'll probably end up with a version of the LAKE EQ in there as well.
"Anyone who lives within their means suffers from a lack of imagination."