First time I'm angry with my Epix. But I'm very very very angry. 
Last Friday I was on a trail in the French Alps. As you can see below, the recorded track is totally mess. At first you may think there was a problem with the GPs signal or the watch settings, BUT... As you can see on the last screen capture, livetrack was active and the track was just perfect on this one !!! So this is just the way positions were recorded into the watch.
I noticed too that the full recording on the Epix was unusual. Points were recorded every seconds (I digged into the gpx file), but the gps positions were static for several seconds (maybe 20 - 60). So the track is not fluid but it is a succession of small lines.
Recorded track
Livetrack
