To challenge a GPS antenna, you don't have to do much ! You just have to make sure that a big chunk of the air basically is blocked by a thick, obstructive and non-hollow material. Example: rock walls, buildings, electric or water towers. Or multiple layers of thin, constantly moving and reflective paper like objects like a tree cover.
Being on a via ferrata route is a good example of this. You are glued on to the rock surface and moving only there, with some adjoining trail sections, for hours on end. Also it is very hand and core muscle focused, instead of your legs, feet and hips.
GPS rays, GPS radio waves can rebound and bounce all over the place, creating a big mess. I already had some very bizarre moments with the Garmin Fenix 3 while doing the GR20 in Corsica. At the end of a day, we had very different data from the watch what my wife was wearing, also a Fenix 3 ! Sometimes 30km difference. We tried doing 1sec and 1minute recording rates to just have a squared out GPS track and similar distance, either way we were moving so slow, that normally getting a signal right was not a big deal. But it was !
And another idea and option to be added to the movescount website: GET AN EMBED CODE GENERATOR ! As I just cannot include a move like you can se above from Garmin. I did try some HTML codes , but I am not an expert in that and have no time to really dig deep into programming, so just like strava and garmin connect, Suunto could include and HTML embed too, for each single move !
Here you go the Movescount link: http://www.movescount.com/moves/move120497078
Try to download the GPX files from each move to a GPS track comparator like http://www.mygpsfiles.com/app/ and you'll see that the Fenix 3 actually gave 59000+ km as distance, pulling GPS track lines all over the African continents while the Suunto was giving a very precise track.
My friend had a very similar experience, not even near tall objects, just on a ski slope around the Parc Vanois, day after day ! Something should be done with the GPS precision of the Fenix 3 ! I am not sure that this is the problem of the Actual Chip, The Algorithme used in the Software or the Housing and type of antenna used, but it should be corrected, maybe in the Fenix 4 and by having at least 50hours of battery life in 1 second recording mode ? That will be the next freckin' giant step ! Epic GPS reception and Enormous battery life !
Either ways, here is a video about the Comparison of the two watches while doing via Ferrata in La Colmiane to arrive to the Baus de la Frema: