What's the battery life like with the Etrex20?
It depends. If you use the brightest screen on constant and they drain quickly, set up with a low brightness screen and they'll last a few days I've found. Better still, as I only use it for unfamiliar places, I switch it off till I get lost. Lasts even longer that way, and I only use it when I need it. (Also, I use rechargeable batteries, so 4 fully charged ones will last me a few days constant use (think LEL), and more in a touring environment, till I can get to a plug socket. IMO the Etrex 20 is nigh on perfect for all day/night Audaxing. Low setting at night on an unlit lane is perfectly visible. I find you have to get your 'zoom' just right, so you get a good idea of where you are as a whole, and also an idea of approaching landmarks/junctions. 1 drawback I have found is the screen isn't the largest, so some people may struggle with reading the map on the move. I had a carp holder for it, and it vibrated a lot. Have since got the solid/stem version and now the display is rock steady. Loads of interweb places to download maps and tracks. Perfect touring/audax GPS. Not as 'bells and whistles' as say the Garmin 800 or MIO 505, but it does what a tourer/Audaxer needs - It tells you where you are, how fast you're going, elevation, what time to the next destination/hill/landmark/waypoint,POI, what time to the finish.