PPCGeeks - New Touch ROM Upgrade

I just got my Sprint Touch. It came with ROM Version 1.12.651.1 dated 9/18/07. I've read most of the threads related to ROM upgrading and have previously upgraded my ppc6700. I want to upgrade the Touch primarily for GPS and Rev. A. WM6.1 is secondary although it would be OK. What is my best course of action assuming I also want a ROM that is fast and can be downgraded, if necessary? Should I stick with the "official" Sprint or should I try a custom? If so, which one? Do I need the use Cokeman unlocker if I want to upgrade/downgrade using the Sprint ROM?