Mio Velo HR senor so far I am impressed, it paired with watch fast. Don’t need to have it on ultra tight. Loving the LED flashing the zone i am in so i can instantly see. It signal didnt drop out while i was on my 5miler. I even switched the app on with my phone so i could see my readout too. It uses BT and ANT+. Here you can see the read out from Garmin and you can see it worked as it should, peaking as i ran fast and dropping when i slowed down. As I own a fenix3 this is a good option to not upgrading to the fenix3 HR model which is £470. I would say that having two devices means less drain on the watch battery, which is important for long runs. Plus the Mio can do what it does well which is monitor the heart rate. The watches features don’t get diluted while trying to be Jack of all trades. So this could be a winning combination. I know you don’t get the running dynamics without the chest HRM but neither does the fenix3 HR watch. Anyhoo time will tell if it is a good choice.