the problems you have with moving 4mm is you fill in all the holes with matchsticks/wooden pegs ect your screws will tend to edge towards the old holes probably giving you an average2.5mm movement.
other problems you may get is if you move the hinges out on the door you are 4mm nearer the edge which may or may not be a problem dependant on hinges and clearence to the edge
if you recess the hinges more into the frame you run the risk that the door will have a more restricted opening as the door will hit frame or wall sooner around the swing
other problems you may get is if you move the hinges out on the door you are 4mm nearer the edge which may or may not be a problem dependant on hinges and clearence to the edge
if you recess the hinges more into the frame you run the risk that the door will have a more restricted opening as the door will hit frame or wall sooner around the swing