Hmmm...
I've been using 21015 for days now and aside from the occasional lag-lock that Bast and a few other have mentioned, I have not had ANY GPS issues. I'm using both TT 915.9196 and GXT 5.00.20W, full NA/USA maps, heavily customized and no issues. Heck, I even had them both running simultaneously the other day just for laughs and giggles as I drove around, and not one problem, though they did suck 20MB of RAM. Thankfully, SSK 15C2 allows me to get about 62MB free after disabling TF3D... woo hoo!!!
My acid test for any ROM is GPS performance, and so far 21015 has been a winner for me. That being said, I will be doing some further tests on 20954, as a number of posts here have pointed to that build being the best mix of performance and stability.
FWIW, I also run PocketShield with S2A dialer, along with about 50+ other apps and have no issues.
I use SASHIMI to do all my cab installs post flash, and currently trying/struggling to finalize full customize/provision using that and CERegEditor (for reg diffs) and Resco Backup Desktop (for file diffs).
Anyways, my point is this: I have used Scott's Kitchen and ROMs on both XV6800/Titan and this XV6850/TGimP platform, and they are-- hands down the best tools out there for the VZW platform
Scott, send U a PP payoff for my "fix-addiction" yesterday, but didn't receive word you got it; please let me know, and thanks again for all U do for this community of Geeks... whoo haaa!
TTFN