I have a very small (5 x 7) bathroom that has the old hexagonal ceramic tiles on the floor. The underlayment of the floor is mortar probably a few inches thick. For the most part the tiles are unbroken and well adhered. I'd like to re-tile the floor but don't want to bust up the mortar bed and that whole mess. I ran across a product called Durock Tile Membrane and they advertise that it will work over existing ceramic tile to give you a good bond to the new tile. Anyone ever use this or familiar with it? I read a few reviews on Amazon and generally they were favorable. I am also fully aware of the height differential this will cause with the toilet flange and the doorway.