If you've got the time you might also want to send details of tcx v2 to the gpsBabel author so that he/she can update gpsBabel to support the new format.
Would it be acceptable to them to convert tracks->courses, as this is what my Python program does?
It'd be nice to plot a track in Bikely than download the course and waypoints to the Edge in one program, rather than using Training Centre to download the course and gpsBabel or Bobcat* to download the waypoints!
I don't know fully the .tcx format, it's another XML derived format. The schema is available online, so I guess the gpsBabel team have access to it. I shall have a look tonight!
*Mac version of Garmin's free route planning software.