I make the track in Mapsource an save it to my Desktop folder I have labeled Routes. Mapsource saves it as a .gdb file. and is it has the Mapsource world symbol shown as an icon.
Then I open it back up, automatically with Mapsource when you double click it. Then hit File and Save As. At the bottom of the Save As window that opens up scroll the selection to .gpx exchange file and hit Save. It shows up with the FireFox icon now in the Route file.
So then I have the same route or track as both types but differnt kb sizes in my Route file. As long as the .gpx file size doesn't exceed the Attachment limit it always works for me.