I couldn’t imagine living without one! So much more robust and durable than a phone, and way better battery life. So you don’t need to worry about it, just switch it on and go.
Mount on my 500 is great and easy to use. In fact I think I got 2 with it, which is nice – making it really easy to swap over bikes. Mount on my Etrex was kinda secure – I thought, until I lost one. The Etrex mount has become worse over time too.
Battery life on the 500, I’ve never reached the end of. And that includes plenty of all day rides, 10 hours plus. Etrex lasts at least 23 hours on good AA batteries (and about 45 minutes on bad ones, I discovered!). I only swapped them over at that point as to not get caught short.
Definitely good kit.