a "false battery" to convert down to 3.7V might indeed be a good idea for those who want both options but don't want to buy the original slim and the super slim also.
I have ordered a quantity of protected batteries to have available for those that want them, once the super slim is in stock. They should fit, based on the measurements you have given Imeo, but if they don't, you'll be buying them all off me, right?

