I don't think the Etrex is well suited for the pilot to use, it is a bit fiddly, only four buttons none on the front, (two either side) you have to pick it up to press the buttons. If it is left in the same mode while in flight, then fine, nice size screen (for size of unit). I'm lucky as our aircraft has a Garmin Pilot with moving map in the front, even then I only use the breadcrumb feature. I'm getting a bit retro in my old age, and enjoy dead reckoning with the map.
Connecting the Etrex to a PDA gives a biggerscreen, but a pain with all the cables, the touch screen can be fiddly, best left for the back seat to play with IMHO.
CC