Last I checked, Spatry said that he didn't quite have the bandwidth for more than the two versions he has now (or something along those lines). However the user could run
sudo pacman -R xfce to remove Xfce4 and then run
sudo pacman -S mate to install Mate. Another option is Spatry could do like what Manjaro does, and set up a folder in his sourceforge for community editions with other DEs and WMs in it.