I used AR3 for awhile then recently switched to the 4000. One big advantage, Nav-wise, is AR3 is fully compatible with Motion-X Drive and the 4000 is not. MXD is as good or better than standalone Garmin units such as the 3597 that I currently use. MXD has remarkable sound quality through your car speakers. It fully takes advantage of the AR3 GPS antenna. I was expecting MXD to make the transition to the 4000 but it did not. The MXD folks said they have no plans to port it either. Shame. I have a backup camera installed and it works fine with both the AR3 and the 4000. I have the HDMI/USB cabl