The Xubuntu team has decided today that Xubuntu 13.10 will not have Mir installed by default. The decision was based on the testing and evaluation Xubuntu team did with Mir before.
On behalf of the whole Xubuntu team, I want to thank the Mir developers for being closely in touch with the team as well as helping with any problems we had. I also want to thank everybody who tested Mir with Xubuntu – all feedback was important. Thank you!
The full logs and the minutes for the community meeting along with the decisive votes can be found at the Xubuntu wiki: Xubuntu community meeting, Aug 22.