Mir works seamlessly (one cursor now) on Lubuntu Saucy.
Code:
ventrical@ventrical-P4M266A-8237:~$ ps afx | grep unity-system-compositor
2619 pts/0 S+ 0:00 \_ grep --color=auto unity-system-compositor
ventrical@ventrical-P4M266A-8237:~$ ps aux | grep unity-system-compositor
1000 2634 0.0 0.0 5664 816 pts/0 S+ 17:54 0:00 grep --color=auto unity-system-compositor
ventrical@ventrical-P4M266A-8237:~$ grep -i xmir /var/log/Xorg.0.log
[ 175.289] xorg-server 2:1.13.3+xmir1-0 (For technical support please see http://www.ubuntu.com/support)
ventrical@ventrical-P4M266A-8237:~$ ls -l /var/log/lightdm/unity-system-compositor.log
-rw------- 1 root root 110 Jul 1 17:48 /var/log/lightdm/unity-system-compositor.log
ventrical@ventrical-P4M266A-8237:~$
edit* Or at least all the code say it does.
Anways ... my comment .. looks like sombody in the Lubuntu camp is eating and breathing and sleeping Lubuntu Ubiquity because ti sure installed very smoothly.