I think Nick is right on. The room makes a huge difference.
AND as a longtime SVS owner and someone who has heard many other subs, my belief is that SVS sometimes sacrifices lower distortion in order to get lower frequency response and/or higher SPL. I think my (older) PB12-NSD is very powerful, but I sometimes perceive it as inarticulate.
Despite what some companies and hobbyist forums purport, I think that subwoofer design and engineering remain relatively complex, and that the performance/satisfaction of subwoofers isn't so easily quantified.
But, you know, I'm just a guy who enjoys music and movies in his living room.
