I can't speak to the dedicated unit because the only one I have is the one that came with my F-150 and it doesn't do traffic and maps are out of date the day I buy a new CD.
But, I just finished a 1200 mile trip using Google Maps and CoPilot simultaneously (not towing). I like that CoPilot I can download the maps and my iPhone has sufficient memory to store the entire U.S. I also like interface better than google maps except for the inability to easily zoom out to a scale of my choice to view the route. May be there, but I couldn't find it.
However, it failed miserably at what it MUST do. Navigate the best route based on the options I set. Twice, it tried to route me through toll roads when I had avoid selected. They were both EZ Pass only and I just bought a new vehicle and haven't called EZ Pass yet so that wasn't an option. It was my fault for following CoPilot that even got me in the area of the tolls because I didn't expect to need to use a toll road for this trip.
Worse, it just gave poor choices and poor time estimates. It wouldn't do live traffic even though that came with premium which I purchased a month ago. On the road I gave in and paid the $10 or whatever for year of traffic. The next day it asked me to activate my free year of traffic for purchasing CoPilot Premium. Arggg. Google maps routed me around a five mile stop and go section of interstate that CoPilot said was a five minute delay and offered no alternate route.
Finally, the last section of my route was my home turf where I know every possible option from point A to point B. I kept using both as a test. CoPilot kept choosing interstate routes even when I chose neutral as my choice and would not offer a four lane state highway as an option that was 40+ miles and 30 minutes shorter. This is not a backroad but a major highway. Google offered that route.
I still have issues with Google Maps and may keep using it in conjunction with CoPilot since I prefer the latter's display and voice commands. Still disconcerting about the toll roads.
