I have an 810 and use it all the time.
The screen doesn’t really suffer with glare no. You do have the option of turning the brightness up/down to suit your tastes, I have mine on 3bars, there are 8 I think, so pretty low screen brightness then. I have bumped it up to max once or twice but that’s really only once or twice. I guess it’s how good your eyes are.
I’ve had a great deal of success with mine, it’s been a god send for my riding.
It’s a well designed piece of kit, the maps (OSM) are easy to read, create and load routes onto/create on then follow. Not too sure what your maps are like but the OSM is more like a car sat nav. On road it’s ace, off road its been ace too. Battery life has been great, never charged whilst using it on the bike if that’s what you mean, you can’t use it if it’s being charged by your laptop and I’ve never tried whilst it’s been on charge via the charger, sorry.
HTH Thanks for that. The edge 305 does not have mapping. You just follow an arrow or a line.
The other key question I forgot to ask is whether you can scroll the map around so you can look at areas that are not currently displayed on the screen?
I use this facility when I go bike packing as it enables you to search for the nearest pub or campsite