can't speak for OP but I've been using a retina MBP since 2014 until this year and I'm typing this from a 4k screen (both running ArchLinux) - everything is fine except the occasional 1997 TCL/Tk app not updated for hidpi
Agree. I've been running Fedora as my daily driver for 7 or 8 years now, and for a while avoided HiDPI like the plague because it was so terrible. These days tho, it's mostly fine except the occasional app that hasn't been updated to support it. Oh, that and the pseudo-terminal (you'll have to squint to see that. Luckily Fedora is so dang stable that I haven't even needed that in years).