I have a Fenix 2 which I sometimes use when Im having a quick flight. I usually use a Garmin 62S.
The watch is good as it measures GPS or barometric altimeter, vertical speed and anything else you need, but only 4 fields display at a time.
The D2 looks over complicated for PPG, with airport codes etc (who flys into an airport?)
Anyway, I use my Fenix for kayaking, cycling and occasionally PPG.