I am running plain Ubuntu 18.04.1 on both machines now. Previously had 16 running but with lots of hassle.
Yes, I also always had lots of issues. But currently stable (which is why I dont even want to try upgrading to the 396 driver or later, as long as I don’t have an urgent need for it. 
BTW: I just thought this would make a good topic on its own, just to realize it existed already, so I reposted my reply there to. Folks there have also managed to set up the same split between internal and gpu in different ways: