If you're returning it for a replacement, I dont think it'll make any difference as I think it's a design/software fault
If for another brand of watch, then fair enough. Shame though as you'd want one you can link to your phone..etc
Similar issues myself. What has improved it drastically, but not always entirely, has been to wear the watch on the INSIDE of my wrist, by which I mean so the face of the watch is on the inside of your wrist where you would read someone's pulse with two fingers. The veins are closest to the surface here.
I also wear it extremely tightly.
See the graph from tonight's nearly one hour walk at a fast pace attached.
I am surprised to see that SAMSUNG is doing nothing to correct this issue. infact they are not even replying to the email I sent. We all should put it aggressively on social media to make Samsung move on it.