What recovery are you using and what wipe options are you performing? I am using RA 2.3 recovery and use a custom wipe zip package that another user created. While the current version of RA has all the wipe options in it, I find it easier to wipe using a single zip file. Then I flash the ROM zip and it's all good from there. With the GB-EVO-Deck ROM I have not had a single issue with the GPS. This was amazing to me as I typically always have GPS issues with previous AOSP ROMs that I tried. My GPS has worked perfectly with the 1.2c and 1.2i ROMs. Looks like 1.2j was recently released but I'm not sure what changes are in there, so I haven't flashed up yet. I do know from the XDA thread for this ROM that lots of people that update their ROM by flashing the new ROM over the top of the old ROM (flash the new ROM without wiping everything) tend to have lots of issues.