I switched from Vivoactive 4, which had an older sensor. And so far the 6 is _really_ disappointing...
It always sticks to certain bpm levels. Mostly around 60, 90, 120, 150. And it is very difficult to get it to "change gear" either high or low. It is _clearly_ wrong compared to a Polar H10 chest strap. And it is worse than the ages old Vivoactive 4. It's a joke, really.