The other observation I forgot to add was wrist based power this is only consistent per activity and cannot be transferred from trail running uphill to flat running for example. You can only set one ftp either for flat running or uphill running if you wish to see your power zones accurately. Going uphill vertical kilometre zone 4 effort near threshold will produce low 200 watt range power for me . A simple zone 1 road run flat road will produce 260 watt power.
I still love my suunto vertical please don’t get me wrong I’m not attacking suunto, actually I’m a staunch suunto defender at all times. I just tend to get to the bottom of things and test everything. And I’m sure these findings apply across all brands if tested enough