Since I mostly run Debian with KDE, I’ve been using it a lot since KWin is on its stable repo.
First time I really use it is on Gentoo, which exclusively runs Plasma. Since it’s rolling-release, it didn’t take too long to be available.
I’ve been moving this build from one computer to another, they all work fine. Currently it’s on a Thinkpad W530. Got some problems with multi-monitor that never happen under X11. Thankfully after I replace the firmware with coreboot, and opted for dGPU only, I never encountered any issue.
Currently, what keeps me from fully ditching X11 on KDE is the buggy SDDM support.
On the other hand, I’ve been using Linux Mint on my work PC. As you may have known, neither Cinnamon and XFCE has it at the moment.