Here's a whacky idea incase we don't get internal sound and metadata on cameras other than 5Dmk3
Is it possible to create a template which you enter your shot details into (f stop, focal length, shot, take etc) and it draws it onto the screen in a similar layout to a slate?
Then - you could have it so that when you record, it draws this on screen for a frame and uses the screen capture utility to capture this information on the the first frame of a video (DNG frame in raw?). At the same time the camera could beep loudly which would be picked up by the external recorder and could be used for syncing?
Then when you record the next take, the take number increases by 1 until the slate is changed?
What do you think?