With ML installed on the sd card my 70D's auto servo will not work; it's looks like the camera does the opposite of what it is supposed to in face track mode. If I move my face left the focus box moves right, then to some random other place in the frame. This happens whether I'm in the ML screen or in the regular Canon screen. If you take the ML sd card out and put in a formatted card the auto servo works perfect so I'm guessing the mixup has something to do with ML on the card.
Also, I do long event shots with my 70D so the auto restart was a life saver. However, running ML makes the camera get really hot (70C), much hotter than it does without ML. I have seen other comments online of user's cameras shutting down from the heat; mine has not shut off yet but is frequently in the red zone.