I have a 4' x 5" powder room. The vinyl asbestos tile is gone. The asphalt "cutback" remains. It's well adhered to the concrete (55 years cured). I have read on these threads that I can use a modified thinset (Merkrete 735 Premium Flex) right on top of the cutback and then lay my 12x12 ceramic tile.
Questions: Will a layer of Schluter Ditra in thinset add anything of value to the tile installation? Can it hurt?