I have noticed very good accuracy on my Vivoactive 3 Music in GPS mode. I have run it in tandem with my Samsung phone and Runkeeper and the two are within a few hundredths of a mile. However, when I mall walk my steps are durn near dead on but my distances are not even close. First, I have my walking stride set via the Connect app at slightly over 30". Last night in "Indoor Walk" mode I walked 3 miles and logged 6300 steps. At a little over 30" per step for walking stride that is very, very close! However, in its typical fashion, my distance showed up as 0.77 miles total! Same kind of thing happens in "Treadmill" mode. Fairly accurate step count but a distance that is short by 50% or so. And, note, that when I am on the treadmill I place the watch in my pocket because I tend to stabilize with my hands. Has anyone found an activity mode that is flat out steps * stride for distance?