I guess Sasuke should be more powerful than Madara, now. This is if it all works correctly and Sasuke gets new powers because even though Madara also has EMS, he is a "shadow of his former self." Itachi mentioned that gaining it would make him stronger because of the new power. That should be the logic of it, but I doubt that this is the case. No way Madara would let Sasuke get stronger than him.