all you should have to do is:
1) Unlock with 2.31
2) Load Sprint "leaked ROM"
3) Run PPST.EXE in the /Windows directory. (sets PRI to 2.03_033) THIS IS WHAT MAKES GPS RELIABLE!
4) Load any GPS/REV.A capable ROM. (e.g. this one.)
After the PRI update, I have great satellite-based GPS, but I still don't seem to really get A-GPS, like I used to on my Sanyo M1... That would give me my location down to 5-10ft in less than a second, always, even indoors. Hopefully our GPS has similar features, but setting GPSMODE=4 still doesn't seem to have A-GPS...
Even without A-GPS, I still get cold locks of about 8-10 satellites in less than 30 seconds. Usually 5-10 seconds outdoors, and 30 indoors. Warm/Hot locks are almost instant.