No, ML is not perfect. I have to reboot from time to time or remove the battery to do so, but without ML I also have to do that, as for example occasionally the evf won't connect or something else happens.
But as soon as the camera booted fine and ML is running, and that is really mostly the case, everything works fine, no dropped frames, no glitches.
I just shot another video for the same brand, and again on the 5d3 with ML, everything worked fine again.
cheers!