HRM-pro benefits for running

Dynamic characteristics of running: the time of touching the ground, the distribution of the time of contact with the ground, the vertical ratio...

... and also a more accurate HR, and VO₂max

And also, more gadgets :)

Thanks all, those are some nice features. I’ll wait for the ru mored HRM-pro plus with probably even more benefits. 

Pretty much any ECG HRM has significantly more accurate HR than any oHR device from the wrist from any manufacturer. If you want to train seriously using HR, you should have an accessory HRM. 

Also consider the Polar H10. It is the most accurate HRM available at retail and has a modular design that is more durable than the Garmin all-in-one design. 

You can replace a failed strap or rotate straps with the H10, while a fault in any part of the Garmin means it is trash. In practice the Garmin ones fail a lot when used heavily in my experience. If you want the running dynamics and Garmin power the RD Pod is an option. 

And EVEN MORE gadgets!)