Just for s&g's, our house in Havasu had the shower tiled in, and the tile was laid right over the greenboard. (water resistant drywall) It was cold in the winter without a shower door so we put one in.
Oh and one more question...did the Hilti hammer break up the slab pretty easily? I have several hundren sq. ft. of concrete in my backyard I am wanting to remove, and I am trying to decide if the Hilti will do it or if I need an Ingersol and compressor.
Did I say your tile looks fabulous?