Don't use the Sprint version, use DCD's ROM... he has an Alltel port for it, no need to try to figure out how to make it work with Alltel. Just follow the directions (unlocker, ROM, radio in that order) and when everything is installed, then just dial *228 and select option 3 to reprovision the phone (this saves you having to enter the MDN/MSID/etc). Then, after the phone reboots, dial *228 again and select option 2 to get the current PRL.
I'm using DCD's WM6.1 2.2.1 (
http://forum.xda-developers.com/forumdisplay.php?f=384) myself on my Alltel 6800... Bluetooth seemed to work fine with my Jabra BT350 headset the few times I used it (I have a Seidio handsfree car kit for in the car, and I refuse to walk around looking like a Borg)
and I didn't even bother setting up my Bluetooth GPS receiver, 'cause I now have internal GPS!
The only issue I have had is that the phone would freeze up if I left it on the charger overnight... we had a discussion about that over at XDA and think it has more to do with the radio than the ROM... otherwise the ROM has been flawless!