I've been using Sierra still and had no plan to upgrade to High Sierra due to hearing a lot of compatibility issues (please correct me if those are now resolved), and even more so with Mojave (thus not even thinking about upgrading to Mojave although I would love the Dark Mode). I have a GTX1080 and have been using Nvidia drivers. I just noticed today that the app that I use a lot no longer supports Sierra and now only supports from High Sierra. AFAIK, the file system is different which created some issues in rolling back as far as I know (again please correct me if I'm wrong) as well as graphic card compatibility. So my ultimate questions are: 1) Is High Sierra now more stable than Sierra in terms of OS when you have 5,1 with GTX card? Or is Sierra still the most stable version? 2) If I want to go back to Sierra, would I have no issues rolling back if I have a Time Machine? Thanks in advance.