Re: Hey Apple, there's another way!
"How much does a "smart battery case" add?"
Pretty much doubles the thickness. Plus it's a horrible, badly designed*, cheap silicone case. If Apple made a well designed leather version I'd be in like a shot.
*Actually make that NOT designed. There appears to be no thought or care taken in the design process, just a case of 'Glue a standard battery to the back of one of our cheaper cases, wrap the whole lot in nasty silicone, job done."