I currently own a garmin fenix 5x for a few years (and love it) and was pondering on getting a Enduro because i do ultramarathons and really love the long battery life. I used to rely on a couple of powerbanks to recharge my Fenix 5 mid race but it is becoming even more unpractical because the battery has decayed due to intensive use and doesn't last as long as it did.
I was considering a Garmin Enduro for longer events and using the fenix for daily use, but seeing how garmin (at least in Portugal) won't just replace the Fenix battery for a fee (instead they sell a refurbished fenix), dissuades me from investing so much on a very expensive watch like the Enduro. The other option is a 3rd party battery from china and replacing it myself, something I would like to avoid but will try out.
I don't understand how perfectly good watches with high quality components are doomed because of the predictable decay of the batteries, when the battery life is a big selling point (in the Enduro it is the main selling point) and it seems relatively easy and cheap to replace the battery.
Planned obsolescence is understandable in cheap plastic electronics but in higher end watches like these it just doesn't fit the positioning of the product.
I would certainly get an Enduro or similar if I am sure that I can replace the battery every few years.
Another option would be a watch designed for ultramarathons and multiday activities with a easy open back case and a quick replacement battery. I'm thinking of my Petzl headlamp or nikon camera. I charge batteries, take a few with me and replace them on the go. Garmin could make money out of selling batteries and chargers for example.