Sub for my system? Please help

Hi I am soon moving to a new house, and am happy with my cuurent Home Theater/Music system, except for the subwoofer. My system is mostly used for movies, but in this new house I expect a 60% Movie to 40% music use. I listen to all types of music, but most is stuff like Dave Matthews, Norah Jones, Patty Griffen, ect... My curent system and what I need a sub to go with is as follows..

Yamaha RX-V2300 6.1 Reciever
Axiom VP-150 Center
Axiom M22ti Front
Axiom QS8 Surround
Axiom QS8 Rear

I currently have a Axiom EP-175 Subwoofer and would like to replace it. Price range for the replacement is $500-$700. As I am sure you know the M22ti's are awesome but a subwoofer is needed, so I have found the sub is more important to the sound of my system then I originally thought. You all seem to have a broad range of product knowlege so I come to you for help and trust (hope) I will be properly guided. My New room is 15' X 19' X 8'
In your budget, you should seriously consider the new Outlaw subwoofer, which was designed Outlaw by Hsu. The sub is sold direct by Outlaw, and it has gotten some excellent reviews.
I would add another ep-175 to the system. A pair will add greater output and blend much better with your system than any single sub could in your price range.

With the money left over pick-up the Outlaw audio ICBM bass management X-over and run them in will need a fairly high X-over setting with the little M-22's anyway so the stereo setting will be a big plus.

I could never go back to a one sub setup in my system.