I picked up a “renewed” Instinct Solar for £100 from Amazon. Been using it for 2 months, with no real clue how it works and how to navigate the various screens. Also a bit peeved that when used biking the buttons frequently get pressed by my wrist/ hand holding the handlebars, and this pauses the Strava recording.
Regarding battery life, was amazed how much power it needs to GPS. Took it off my wrist on one ride, to avoid abovementioned button problem, and stuck it in the rucksack with 27 days battery life showing.
Discovered that it used those 27 days battery in about 3 hours and then shut down mid route.