I have no idea about the limit and exFat as my camera doesn't support it so I have never tested it. RAW shooting does support recording larger that 4GB it just writes out multliple files that you can stitch together later. If you are shooting in RAW mode it should work, if not ML can auto restart recording a new clip once the 4GB limit has been reached but there will be some lost time.
EDIT: Does the recording stop or does the camera turn off? If it turns off you need to set the camera's auto shutdown time to OFF, raw recording works in a different way so the camera will turn itself off when recording long clips if this option is not turned off. I imagine since the camera is being hacked it doesn't know that it is actually doing something when shooting in RAW mode and shuts down to save battery.