@Brad_Olwin
I’ve not been able to do any very long activities but based on testing endurance mode on the S9PP on 6-7 hour runs my conclusions are:

In endurance mode (half power), navigating a route but with no ETE/ETA/distance to waypoint fields in the sport mode, the S9PP stays in endurance mode for gnss fix. Battery burn rate was equivalent to 65-70hrs.

In endurance mode, navigating a route and with ETE etc fields in the sport mode, the S9PP switches to performance mode for gnss fix. Battery burn rate was equivalent to 40-45hrs.

Further supporting these conclusions was the comparison to the Garmin Enduro I wore at the same time. In the second case, distance measured agreed to within 0.1% compared to the Enduro, which is similar to what I normally see based on many comparisons in performance mode. In the first case, the difference increased to 2.5%, which is not surprising if the S9PP remained in Endurance mode.

I don’t know if this is the same in the Vertical in the equivalent low power mode (ultra?) or why the S9PP switches when ETE/ETA fields are included. It’s not necessary given it’s accurate enough to navigate a route in endurance mode. There were no other differences that would account for the change in burn rate.

If you’ve done any testing with your watches or had any feedback from Suunto, I’d be interested to hear. I’m not going to buy a Vertical yet because the replacement HR sensor on my S9PP is bubbling a second time. So I want to wait until I’m sure Suunto has fixed the sensor bubbling issue (3rd time lucky for me hopefully!) before considering another watch.

Suunto Vertical battery modes