I've switched over to SportTracks and, as advertised, the elevation corrections to what my Garmin Edge 305 was outputting to Garmin Connect are significant.

1. How does SportTracks calculate elevation gain (USGS?) and is their calculation considered to be closest to the true gain?

2. Do the newer Garmin units (500 and 800) calculate elevation more accurately or is the elevation overstatement a bug in the Garmin Connect software?

Thanks