That's why I wrote "if you just want to follow a trail". I think it can do HR but I've never tried. You can customise 'navigation' fields and show compass and lots of other 'nav' stuff.
Sure. I should probably look at one out of curiosity. I know most old skool guys use them, like Kristof, Jesse and most of YACF. And the AA batteries thing is handy.
I want data fields too. I don't think etrex does power, does it?
But it would work as a backup map with phone as the main navigation.