I had two of these - the plus versions actually - in my old theater. I actually still own them. They are in a theater in a house I rent out.
They are very weak performers and they drop like a rock from 30hz on down. Worth maybe 150-200 bucks, but nothing more.
Here is what I wrote on them back in 2007
"For what it is worth, I have two of these subs in a 17 x 19 x 9 theater room. I paid $400 each for them on ebay two years ago and I would rate them as average at best. Although they have a 15" driver, as has been mentioned, they just don't move much air at all. They roll off pretty sharply at 30hz and they have little output at 20hz. Infrasonics are slim to none, in my experience. It is not just a placement issue - I have put these subs in at least 10 to 12 different places in my room trying to get some better performance out of them, but with little success."