Just bought the Klipsch. Couldn't find much info on these forums, but some professional reviews around the net were excellent. Would have bought it even if I hadn't come across those reviews. At this price, this is definitely a good deal. The sub is above 700 dollars everywhere else. Was going to buy a sub today anyway, and I think I got lucky with this deal.
I honestly doubt a regular priced 350 dollar sub from HSU, eDesign etc., will outperform this one. They may be similarly matched at best. I know people on these forums hate the assumption that a higher priced speaker/sub will be better. But I doubt my ears will tell the difference. In the end, even if this Klipsch performs at the same level at a highly regarded 350 dollar sub, the fact that it a better known company among regular consumers will make it easier to sell.