You'll want to update to the latest firmware before flashing 3.1. The devs recommend being on the latest for the best user experience. I highly suggest going for S-off Crit. Its really not that bad and if you get stuck we're always here. Seriously you want to be S-off for the long haul. Every OTA throws a monkey wrench into the gears, and it seems to be getting harder for the devs to get everything working right afterword.