It seems Garmin's grade field has really improved. IDK when it happened or with what rev, but I find it to be really good now. Going way back I used the Sensible Grade IQ app as it was much better than the Garmin's grade, which lagged and was all over the place rarely corresponding to the grade I was actually riding. I don't remember what prompted me to compare them recently, but I did, and found Garmin's grade really improved, to the point I like it better than Sensible Grade. If you gave up on Garmin's grade field in the past, you might try it again and see if you think it's working reasonably well now.
