Depends on what version you're on and even then that's not much of a big deal if you're already rooted.
You can simply make a backup in recovery and flash a newer rom. If for some reason something goes wrong it's as simple as restoring your backup.
What may get a little tricky is whether or not you need to flash an updated radio. That depends on what version you're on now.
In your shoes, I'd go ahead and make a backup of your current rom, flash a newer rom and then see how that runs. If you don't have service/data then look into flashing a newer radio.
Sent from my SCH-I605 using xda app-developers app
Originally Posted by zenulator
We > HTC
Rom: Mjolnir v 3.2