I have a feeling EMS is not as simple as it look's. why? well look at the fact's we have never seen Madara/tobi use it, also if i am tobi(master mind) why in heaven's would i want to have someone near if not equal to i am to use EMS, that would threaten my goals and plan for domination, and sasuke has a history of being a back stabber, madara know's this. one thing i don't understand about madara, kishi showed that he had a room full of sharingon's in episode/216;i am willing to put money that EMS has either a life risk, or a certain usage which means the wielder cannot using ever again after that time period. that's why i feel that madara kept his a regular sharingon on and he went for rennigon. if he doesn't have it he could have took sasuke in the surgery and if he does have it, its ability may be a one time thing. but what do you guys think? will sasuke use it against naruto and in the heat of battle say "oh sht wtf? my eye's or will the eye live up to it's reputation. (over all i am very disappointed with kishi and the fact that byakugon doesn't have a upgrade since sharingon was said to come from it. i won't argueWTH about rennigon because it's basically the king of all eye ability's.