I drive all day for a living. Not over the road trucking type stuff, but residential address seeking type stuff. I've been using Motion Pro for 2 years and it's acceptable, but I don't love it. I recently started using Waze as my gps, and so far it's working well. And it's free. I didn't read the whole thread so I don't know if it was already mentioned or not.
Waze is sort of like a social GPS, other users in your area add input like traffic jams, accidents, visible police, etc. them as you drive, it will show areas of your route in red that are potentially going to slow you down. When you stop at lights and don't need the navigation, it pops up traffic info around you, like "Wazer user reported visible cop on RT 79 near X exit" Wazer user reported traffic stand still at Hemlock road in Cranberry" that sort of thing, once you get moving, it goes back to navigation mode.