I don't know, that makes very little sense. If you'll never use the full potential of a SUB 2, or the SVS PB13-Ultras, then you don't have a proper home theater room to begin with. So in that case, one should be looking at the less expensive models on the list. On the other hand, if one can afford a $9000 SUB 2, then it's ridiculous to believe that he/she cannot build, or dedicate a proper home theater space.
I think SPL and distortion are two of the most important attributes in a subwoofer. Sure, the Q is important, but everything on that list is flat as a ruler. What about EQ? That can be done via XT32, etc.
Even two PB13-Ultra subwoofers will give the SUB 2 a run for it's money. More even room coverage, etc. And they will do it at less than half the price!