Ben it's too bad the sound coming from that room is less than satisfying for you, especially with the cash, and time, you've put into that space. Don't know about the budget, but here are some options as I see it.
1- You're still inside the 30 day window with Axiom, consider the new line speaker. Nearly doubles the drivers, with an additional 6.5'" woofer. Earlier talk on these new speakers, stated they would need too be pulled out from the wall as much as two feet or so. This would increase the woofers by one, and places them closer to your seating area, not to mention what it would do for the mids, and highs.
2- I know you mentioned earlier you only had one DIY sub. Could consider going with two strong subs, start off by placing them on adjacent walls, then altering their positioning until you find the best room response.
3- Are you presently running a power amp. If yes, is it enough to drive those M80's. If you're relying on a AVR to do so, it could be an overwhelming task to power this new system, in that new space. Besides the M80's, you have now added two more surrounds (QS8's) into your setup configuration.
AS you can see Ben, I'm being really free and easy with your money.
But seriously it's going to take some $$$ to give you that sound you're looking for.
