Bought 610 1.5yrs ago and used it all the time and loved it. As I do triathlons and swim open water I decided to sell it and buy the 910. I wore it once and didn't like it. Too big for my wrist and I really missed the touch screen features. So, I sent it back to Amazon and got another 610! I use it for running and cycling and the data feeds back to my coach in France to analyse. Sometimes the HR is incorrect but not often. Easy to upload data. Love it to bits.