And no problem when riding with others with the same model?
polar HRM's are individually coded with something they refer to as 'own code'. In my training bunch, the majority of us have polars from 625's, 710, 720 & 725's. we don't have any issues with 'cross' information. The wireless 'pickups' on these models are all the same, only the 'features' of the actual 'watch' units changes. Like all 'wireless' bike computers, expect some interference from high voltage overhead wires. Other than that, I've never had any issues with my 720,