I and several guys in our forum have one problem.
There are very poor Bluetooth in Sapphire version.
I had Vivoactive HR before and it's worked well in radius of 10 meters. But F5 Sapphire is losing connection even 1-2 meters. It can disconect than you telling by phone in right hand and watch in the left hand.
It's very annoying. Function "Find Phone" is unmeaning in that case.