On these rotors that are offered with cad plate.... are they cast iron rotors or steel rotors? If you CAN get it, it's a superior plate... very corrosion-resistant. The original Ford Model T's used it on fasteners. And they also use it on naval aircraft. You wouldn't want the plate on the working surfaces. I don't know how the plating process would result in brake pulsation, unless the working surfaces were plated.
Grit blasting is a wider term for sand blasting.
95 E320 Cabriolet, 131K