My main problem with multi-monitor on OSX is little mouse cursor freezes that happen every few seconds while I'm using it. I've searched and found that it had to do with multi-monitor but have yet to find a solution.

Compared to this Linux isn't all that bad. Took me a bit to find the magic xrandr invocation that would allow me to manage screen pseudo-brightness sanely. If I can find out the right way to put together a f.lux-style Night Mode I may switch to Linux on all machines.