You could do that but there's no guarantee that your device will read that gpx file and understand the routing, the same way that the program did. When I bought my 660 everything I read about it, from the most knowledgeable sources I knew, the Bsecamp tutorials, and GlobeRiders stated that it wouldn't use shaping points. It would simply route you from one waypoint to the next using it's own algorithms. One work around was to export your gpx file from Basecamp, import to MapSource (older discontinued Garmin program), and then upload to your device from Mapsource. This made sense to me as Mapsource and the Zumo 660 were from the same era, and I was fine with knowing that limitation and workaround. Using Basecamp with it's updated routing algorithms like curvy roads etc. were not supported on the older software running on the 660. It can be as simple as a routing program using a tag that the device doesn't support, or just ignores. I think that's why Ed in his Basecamp tutorials suggests routing using waypoints, it goes back to the basics and a known entity that ALL devices and routing programs/algoritms WILL support and use CONSISTENTLY, taking the guess work out of your route planning. Then the newer devices came along with their new programming and routing algorithms that support more advanced routing. These may work perfectly with your routing program of choice, or they may not.