Just done 3 rides with the 520, and very pleased with it "on the bike".
But have had 2 out of 3 rides with problems when imported into SportTracks, it is as if I had "a million pauses" during the ride... Thus it cuts several minutes and gives a way to high average speed. I do have autopause on at 3 km/h , but there is no false pausing when riding, and the timing in GC and Strava is as close to one another and the Edge as it can be.....