I honestly do not think that you can beat any speakers from Bryston. Your room would do very well with the Middle T which will fill that space wonderfully. I had a pair of them in my 10,000 cubic foot space, which has an 18 foot high vaulted ceiling. They were so good that I ended up trading them out for the even larger Model T. If you want to get a similar performance to the Model T, only with smaller woofer drivers as you do have a much more limited space constraint, I'd look at Axiom Audio's website and read about their LFR1100. I know a couple of guys using them and they rave about this speaker. BTW, Axiom Audio builds all of Bryston's speakers. I am currently using the upgraded Model T with the fully active inputs, however I use the monster PX-1 external crossovers which are built on mil-spec pcb's with massive air core inductors to handle pretty much any power level you can put through it. These crossovers were designed for use with Bryston's 28B3 mono blocks which put out nearly 2000 watts per channel. I am using Anthem M1 mono blocks running on dedicated 240 v/15 amp circuits which will allow for 2000 watts per channel with virtually no distortion.
Axiom Audio is up in Ontario and they build everything in their facility, there are no 'imported' parts. They also offer a 30 day trial period and if you are not satisfied, they even pay the return shipping on the speakers; but I doubt you'd be returning them :). Its a no risk purchase. As you can read, I am a huge fan of their products! In fact Ian (the CEO) just built me a custom center speaker out of their M80. He made the cabinet in Knotty Pine veneer to match the area I placed it along my staircase and in a size to fit the area. It is gorgeous! Anyway, give this company a close look; check out their web site.