FWIW, choosing the M450 will enter you into the Polar ecosystem via the Polar Flow app and website. That may not be a bad thing as the Training and Recovery stuff sounds interesting. Garmin Connect and Garmin Express act mainly as a ride forwarding system for me and other Garmin users. Looks like Polar Flow uploads to Strava, but how about RidewithGPS?

Guys like me think about other considerations, though. Check out this image:



Three devices are capturing heart rate simultaneusly from a dual band strap: a smartphone via Bluetooth LE (aka Smart) and two Garmin Edge 500 bike computers via ANT+. This just simply would not be possible with a Bluetooth Smart head unit such as the Polar M450.

Bottom line: due to BLE protocol limits you could only operate the Polar M450 solo with a bluetooth heart rate strap. A fitness tracking BLE phone app will not connect once the strap pairs with the M450. Redundancy is not possible! Minor point, I know, but an important one to data monkeys.

Now let me get back to checking out my heart rate on three devices while I ride. (The phone goes in the jersey while the second Edge attaches to another bike, actually).