Your Garmin help, please

I for one would be really interested to hear how it copes with you mental audax types :)

It's very good for the really long stuff. It copes with very long route files and ride recordings (longest so far is 660km). It's also fine about being plugged and unplugged during recordings. My old 810s would brick themselves if I tried anything so bold.

I've also found the battery to be pretty decent too. 10-12 hours using the map screen, but it recharges very quickly (I'm guessing it's relatively small capacity but fairly energy efficient).

Another benefit for audax riding is the ability to navigate using the LEDs. That means you don't need to have the screen illuminated during night riding.