Thanks again. A follow-up: I think my phone is one update behind. I'm running T839UVKD1, and my googling tells me there's an update that came out 12/12.
If I use kies to flash that, I understand that I'll lose root, but will I lose my unlock?
Also, is the update worth it? Despite the complaining over at the TMobile Sidekick 4G forum, I have few complaints about the phone or the stock ROM. I've frozen Google Maps, Group Twitter, and other resource-hungry apps that I'll never use, and everything is generally fine.