Hi,
For 36 hours I've been using 18.16. I've upgraded from 16.22, did a soft reset (15 seconds light button) after the upgrade.
So far, no problem. After the upgrade I've done a bicycle workout, with GPS on. I've the Incident detection configured. The battery app/glance saying 0.145%/h usage after the 36h (with 8h of battery save mode).
I did not yet test the HRM to check for possible connection problems. The sleep detection/score is correct, as well as HRV. There was no drop of Endurance Score.
Maybe I'm lucky, but this 18.16 version is in my case quite stable and without any bug that affects my usage.
Best regards,
Miguel Anjo