I use KDE on 4K at 200% too. On FreeBSD with X even, at the moment :) Though for work I use Linux with Wayland.
It's true that the mouse doesn't auto scale but you can manually make it bigger in settings. Same with the "taskbar" height. HiDPI is still a bit in development and I heard the next release 5.23 will bring a lot of goodies in October. But overall I think it's fine.. Where it falls down is mixed DPI (e.g. one screen at 200% and another at 100%). But even Windows is still very flakey with that. Only macOS covers that scenario perfectly.
One thing I love about KDE is the wealth of options. Gnome is heading the way of Apple: opinionated software and minimalism. Windows is heading the same way though not as strongly. That doesn't suit me. KDE is really my thing.
It's true that the mouse doesn't auto scale but you can manually make it bigger in settings. Same with the "taskbar" height. HiDPI is still a bit in development and I heard the next release 5.23 will bring a lot of goodies in October. But overall I think it's fine.. Where it falls down is mixed DPI (e.g. one screen at 200% and another at 100%). But even Windows is still very flakey with that. Only macOS covers that scenario perfectly.
One thing I love about KDE is the wealth of options. Gnome is heading the way of Apple: opinionated software and minimalism. Windows is heading the same way though not as strongly. That doesn't suit me. KDE is really my thing.