So I've been on Ubuntu 18.04 for a few months and have become quite comfortable with it.  The biggest pain point has been adapting to the Dell's keyboard layout and developing the muscle memory for Ubuntu's keyboard shortcuts.

The second biggest pain-point is PDF support.  On the Mac I used Preview for all kinds of stuff - from signing (placing graphic of signature) to manipulating pages (inserts from other files, deleting pages, etc.).  I never realized how bad the support for these features are on other platforms.  It's not just Linux but Windows too: even the 'free' Adobe reader doesn't let you do what Preview does without paying to upgrade.  Apple got that one right.  So far this is the main reason I have to fire-up the OS X VM.

Would I go back?  No way.  Ubuntu has its quirks but I have yet to get a panic or freeze.  My two gripes are WIFI only rejoins about 50% of the time waking up (you have to turn off & back on, sometimes twice) and the keyboard mapping for suspend is right next to the FN+END key (Insert); but that's somewhat of a muscle memory thing.

I'm committed now: I sold my 4-year old MB Pro and got more for it than the 2-year old Dell that replaced it.