I recently got my Dangerbird 72, as well...so far, just house-hanging, but with the AC set to hit the mid-70s at night, it's about the same as if I were sleeping outdoors at the moment.
I reused my New River full-length underquilt, although I did have to let out some slack at the ends (the DB 72 is much longer than my Blackbird), it worked out okay. Initially, I felt like I had an air gap under me, or that it would easily slip off of me with all the extra side material to slide along, but I rigged up 4 shock-cord ties with a carabiner and cord lock, ran that through a couple of the side loops on the hammock, then clipped to the underquilt and tightened to make sure it was positioned under me.
Having 4 adjustable points made it much easier to make the underquilt match the direction I was laying, so I was very warm that night.
"Can't we all just live in trees and hammocks?"
-- Sam Gribley, My Side of the Mountain