Everyone compares the speaker size of the Q700's (6 1/2' woofers) and say one should get the Q600c. Well, I have the Q200c with the Q700's and it is perfect. That logic makes no sense really. My Q200c has NO problem keeping up; it is not even an issue.
Initially, I ordered online and received the Q900's and the Q600c. First of all, I have NEVER seen such a freakishly HUGE center channel in my life. You could have put a 12' woofer in it and called it a subwoofer! It would not FIT in my TV stand (open 3 tier glass shelves).
The Q900's made my 60' inch flat screen look like a 42 inch TV. I packed them all back in the box the same day. I am talking I could have put both of my 4 year old twin girls in one speaker cabinet. Wow!
My Q700's rock and have excellent bass and the center is amazing. Good luck.