The biggest thing I can think of is that X11 is more flexible when it comes to specifying custom resolutions; which some people use to output 240p on CRT TVs for emulation. AFAIK, there is currently no real equivalent for xrandr on any Wayland compositor.
I’ve also noticed that Grsync’s password prompt is broken on Wayland. Thankfully, it has a feature that lets you preview the command it’s about to run, so that you can copy and paste it into a terminal.
Being a KDE user on EndeavourOS, I use Wayland everyday. I switched over a few years ago for Waydroid, but now X11 isn’t even an option for me with the current release of KDE.
Wayland can sorta do all three, but they’re effort to set up and sometimes have bugs, whereas it was perfect under X:
1: Rotate, flip or scale a display.
2: View a window on a different computer
2.5: View a window on a different computer that’s already alive.
3: Overlap two displays.
@Aria @mrbigmouth502 But what X didn’t do while all that was going on was use two different GPUs to make the graphics all smooth.
That’s true. But you can run X twice and that way use two GPUs for two independent windows. I feel many of the advantages to Wayland need to be explained or measured, whereas the advantages of X can be experienced.