Another fan of dcrainmaker here. What he doesn't know about these gadgets isn't worth knowing. If I thought I needed a GPS watch, I would browse his site for info.
Personally, I just use the native Workout app on my Apple watch. My watch is the early version without a GPS chip. But it synchs up with the GPS in my phone when the phone is nearby. If you take the phone along for a few workouts, the watch calibrates itself. It's pretty clear how that works. As you are walking or running at various paces, the watch is getting smarter and smarter about how to evaluate variations in your stride length and about how that translates to distance covered. After a few workouts, you can just leave the phone at home and still get near-GPS-level accuracy on how far you've traveled.
