I have the setup you're looking for. At first, I wasn't so sure about the servo subs (open baffle) compared to sealed subs, and I have to say I was dead wrong about those concerns. I'm using the LFE inputs on the Servo Sub 4s at the moment with possibility of switching to the high-level at some point, but for now I can say this is the BEST sounding theater I've ever configured. I had a guest over the weekend who said that my sound system rivaled a $500,000.00+ installation he contracted (he was the contractor for the theater, four rows of four seats, but pulled in an outside company to do the electronics). That was the best feedback I could have ever gotten, and I'm not even done with it yet! I still need to build and install the A/V-1RS speakers.
So you can't go wrong with Servo Sub 4 kits. Amazing. Worth every penny (and the time it took to build them).
Waiting to be built:
EDIT: Side note, my room dimensions are similar to yours, so the only thing I would consider eliminating are the ceiling speakers. My ceiling is 9' with a 12" riser. An 8' ceiling might be too low for a 12" riser depending on how many rows of seats you're planning.
