Shivas:
You are spot-on in your addition of the 10th Hole at Butler. It is not open to discussion - the 10th hole at Butler from the back is the hardest Par 4 in the Chicagoland area by far. I would argue that it is 1 shot harder, on average, than the next hardest hole. I've never seen anyone birdie it. That hole is so damn hard that Oklahoma State's coach, during the last event there, REQUIRED, that every player on his team lay-up their second shot short of the water and then take their chances getting it up and down.
AI do have to disagree with you on Medinah's toughest par 4. I have to give it to #6....and, after the changes, it's going to be even harder....then again, with a new back tee on #16, it may get harder as well (although i think 16 will get more playable as better players will be able to hit a full tee shot with the new back tee).