DaveN,
The widescreen review article really had me excited about the MTX. But when I measured it at the store with my SPL it didn't have the extension I hoped for. Also, no matter what I seemed to do there were higher frequencies coming out of it and it was just too boomy for my tastes. However, if you are pleased with its performance bully for you. I have an ACI Titan which I am very happy with and few other people like so, se la vi.
Also, I just wanted to remark on the Acoustic Research subs. I had the 12HO (or whatever) in my house and what a piece of crap! Measuring the response with a SPL meter showed it had extension only down to about 45 Hz. Then nothing at all until you got down around 30 and then it was just buzzing and distortion. While it's possible I got a bad unit, it was nowhere near the specifications said it should be.