i'm running 4.5.0.56 on my Alltel 8130. Runs great! Html email, docs to go, and a little less memory leak.
All in all a winner IMO. Don't be afraid of it. Not real difficult to upgrade if you follow the directions you'll find by searching Crackberry.
You'll grow old and grey (or older and greyer!) if you wait around for Alltel.
Good luck to ya!
Posted from my CrackBerry at wapforums.crackberry.com