No, I have 4G disabled. I hit this problem last week.
Took a road trip from SF, CA to the canyons of Utah. With GPS (google maps) running, if I started the music app and played music (mp3s, no use of network), then the GPS signal is immediately lost. Pausing the music brings the GPS signal right back.
Of course, we were in the middle of nowhere with no radio stations, so it was very quiet for a while. Suckage.
(Oh yeah, and google maps is useless unless you load up your route in a town with 3G before leaving ... AND DON'T BUMP THE BACK BUTTON!!! Gawd, could they please put a confirm cancel route dialog box in there ...)