I have the Sunfire MK II sub in the similiar setting. I am totally pleased with the MK II's performance both with music and home theater. It has all the bass I need and then some. See if you can borrow the subs and test them at home before you buy them.
Sunfire True Sub Jr. VS. M&K VX-100
I need a compact sub and was wondering if people had any thoughts as to which one of these is better? I am mainly interested in finding out which one is better for music, although home theater is a small part of the equation as well. My room is large (cathedral ceilings etc. but the listening position is barely 8 feet from the speakers). My main speakers are PSB Stratus Bronze (which go down to around 40 Hz). Also, because of severe space limitations I CANNOT consider full size subs. Input on the True Sub MK II as well would be useful. THANKS!!