Just bringing my two cents on the Ultratrac mode.
Before anything else I just want to say I'm very happy with my Fenix 5S plus, even with the battery life (getting approx one week with two to three hours of GPS activities + daily smartwatch mode). But as most users I was expecting a top range device like the fenix 5 to manage a full day of GPS, for trekking or ultra trail, software wise - with a decent compromise between GPS accuracy and battery consumption. Unfortunately the consensus is that Ultratrac mode is VERY far from that.
I would be happy with a drop in accuracy if the GPS data was still a little relevant, but all the reports I've seen give distance gaps of more +50% (33 km instead of 24 for example) and GPS tracks look like drawings of my 2 years old boy
Competitors have developed similar modes which are much more intelligently coded (Suunto 9 ultra mode ?).
So to me, Ultratrac is just a marketing name, not yet a feature I'm even considering to use. I prefer packing a small power bank in case I run out of juice during a trek or trail race.
Has anyone got a positive experience with it? Any setting or type of activity where it gave relevant information ?