The thing I liked about the DNN series that Mark posted over the DNX series is that it will connect via wifi or a hotspot. So when it's parked in my garage I can turn it on to update maps/routes I made while sitting at my computer as opposed to having to re-make my routes when I get in the car. I think that's the only main difference though so i'm not sure i'd pay $300-$400 more for it. We'll see how the prices look next Christmas

From what I can tell, the GPS & traffic data is automatically updated without hotspots... i believe it uses one of the FM digital channels.

Steering wheel controls isn't an issue, there's an adapter for that. I'm not sure about keeping the stock backup camera, but that's a non issue for me since I can't see out mine anymore and want to get an aftermarket one.