Finish those bass traps! They will make a huge difference. I don't know if it's the IB or the room treatments, but my system sounds much better than anything I've demo'd in the local high end stores. Bass is well defined and sharp. Powerful when needed (i've worried about the drywall cracking while showing off).
Why IB? Effortless sound. Crisp transients. No hint of boomyness or muddiness. Music sounds so much more real. The upper bass/lower mids sound cleaner.
http://home.earthlink.net/~afordfan/id1.html