I actually just returned a pair of pb2000. Tried them for 45 days and was pretty happy with movies but felt like I could do better for music. Only reason I am considering buying another pair is because of the BF sale. I originally paid $1400 for two from the outlet and now can get 2 brand new for $1200.
Having said that, I do realize that I am unlikely to see an improvement in musicality moving to a single, larger sub. I have also considered getting 4x rsl speed woofers (because it seems like an interesting thing to try out).
My space is strange at the moment. About 18 ft across and 24 feet long and the back opens up to another room. Not ideal but I am moving in a few months so this space is temporary.
Subs will be run at 80hz with Polk LSi 9s and a Denon 5308 receiver powering them