BlackBerry PEARL on TMobile with Bluetooth GPS receiver

Had to drive from the SF Bay area to San Diego today. Tried using a bluetooth GPS receiver (Belking Xtrac/Fortune ClipOn) with the Pearl. The Pearl comes with mapping software out of the box. It relies heavily on GPRS and EDGE to download maps and data on the fly. Driving 80mph, with zoom level on 3, it sometimes doesn't quite update the maps fast enough. No navigation and with auto mapping. What it is actually doing is downloading the maps and them super imposing your coordinates onto the map. More on this later! Battery life with GPS and GPRS was about 5 hours or so.