For various reasons that might be explained in more retroblogging, around January 2014 I got fed up with OSX and decided to switch back to Linux. I got things more or less working on my Macbook Air. (Later, in 2016, replaced with a Macbook Pro.)
TL;DR: It's okay, and a bit smoother on the Pro than the Air, but I wish I had hardware that I know everything works out of the box.
I've added two pages: Linux on Macbook Air and Linux on Macbook Pro and hope they are useful to others.