Globalmenu, dockbar and custom themes work on xfce very good. The panel is fast and configurable. Except some small changes of some css files it is very compatible to Mate themes. Thunar seems to be stable too. The Xubuntu Minimal can be configured as snap free as Linux Mint after install. I Like it very much in a vm. Now im thinking about installing it in two months on my real Hardware.
BUT:
In the past i had a strange menu transparency glitch on real Hardware depending of the gtk theme and some window placements where different from the metacity or later -mutter-/Marco?.I know it can be fixed somehow with Compton but ..
Gnome and cinnamon now use a new mechanism using the gtk Theme itself. Unity used a css approach also.