The 8830 has Blackberry Maps installed on it. You can also use Google Maps, Mapquest, and Yahoo Go! as well and pair it up to the GPS receiver to get GPS tracking. With the GPS receiver you could also use TeleNav and get voice turn by turn directions.
With the MotoQ, you could also use Google Maps, Mapquest, and Yahoo Go! as well. You may even be able to use TeleNav as well after pairing it up to the GPS receiver.
Overall, I think that the BB has a more stable OS and will require less reboots. But you may be able to get a few more 3rd party full GPS (voice activated) software solutions for a WM device at this present time.
Hope this helps.