I got a 44M-4 about a month ago along with a fotodiox adapter for my 5d mkii. It does have mirror hang so I put a very thing rubber band in between the adapter and the lens.
The mirror hang depends on the size of the mirror, which varies a bit from model to model. Apparently, the 44M-4 hangs right at infinity on some of the 5D series, but it doesn't hang on the 6D as far as I can tell.
The 44M, by contrast, hangs noticeably at or near infinity on the 6D, so I always make sure to use live view mode if I want to shoot near infinity (and make sure to focus away from infinity before I leave live view mode or let the camera doze).