I would never buy a built in unit of anykind myself. I have too many vehicles. I like the fact that I have one unit, one price that I can use on any of my vehicles. I use the Zumo by Garmin....waterproof, vibration resistant, motorcycle mount, car mount, and I can easlily move it from car to bike to truck to rental car to rental bike.....whatever.....have used it in airplanes, hot air balloons, hiking, where ever.
If I had a built in unit it would only be in one car and it would not support any of my other activities.....and it would be more money for no more performance. Of course I feel the same way about my sateelite radio units too....one for everywhere....why pay extra subscription fees for each vehicle.
Only 600 more miles till the Arctic Ocean....
