Hey Gene, have you contacted Elemental Designs or Tweakcity Audio? They have finished subs which I think would be very competitive. You should really contact Mark Seaton too, if you haven't done so, the Submersive definitely deserves a place in a comparison like this, as I have heard nothing but praise for it.
As for the PB13, back in the day I think SVS would have been chomping at the bit to participate in a comparison like this, but nowadays the competition is much stronger for the around same price point. They just don't have as much to gain anymore in a shootout like this. I'm not saying the PB13 isn't a great sub, I would love to own one, but you have to admit there are other very compelling alternatives right now.