I have never been able to see any effect from aGPS (or cell triangulation, but I don't think that works at all on the TP) set on or off. Radio / ROM don't make a bit of difference. I work in a building with very few windows and when I am in certain areas there is no way I can get a lock. But, my junky BB Curve (sprint service) gets locks nearly instantly.
I've tried Sprint's agps settings, only to find them locked down to Sprint phones (or phones with Sprint service at least

D)
Also tried Verizons from the aGPS provisioning cab, etc etc...
jmorton, I'm curious what your gpsone / registry settings are. Mine are set as in the CAB:
HKLM\Software\HTC\SUPL AGPS
<parm name="ServerIP" datatype="string" value="66.174.95.132"/>
<parm name="ServerPort" datatype="integer" value="8888"/>
<parm name="GPSMode" datatype="integer" value="4"/>
I know I'm missing something... does anyone have working aGPS settings for TP on Verizon? I've read that the Telus canada servers might be an option, but I wanted to see if anyone here was using them.
Overall, the GPS works great on my phone (slight lag) and decent locks if I am outside.
I did have some crazy incident last week (while travelling and actually needed it!!!!) where the GPS couldn't get more than 2 sats... quickgps and booting didn't do a darn thing... then 20 minutes later it worked fine, but for this I have 0 explanation... even the sky was clear. I had to power up my laptop and bust out the USB GPS adapter to get where I needed to.
If anyone does have an answer for this, please let me know. For some reason I can't seem to let this go as this crappy Sprint BB Curve can get GPS locks I can only dream of.