If you are interested in purchasing an H10 for use with your VM3, it will work perfectly, IF you choose an activity. If the H10 is paired, but you are not currently in an activity, the connection will drop after a few minutes of idle time. At least this has been my experience in the past day of H10 ownership.
If you want to use the H10 in place of the wrist sensor when not exercising, just choose an activity and don't save it at the end of your monitoring period. Other owners may have different experiences, so please chime in if you do. For me, I am only interested in using the H10 when exercising, so I am ok with this.
The great news is that the H10 is superior to the VM3 wrist sensor in accuracy and response. I checked the H10 against the two-hand style heart monitors in the treadmills at the gym (new Life Fitness model), and the H10 tracked faster and was within a beat or two. The VM3 wrist sensor was nowhere near as accurate as it could stray 10 or more beats away from the treadmill, and it wasn't nearly as responsive - plenty of lag.
Hope this helps another new H10 owner!
