My husband did it last year and it rocked his world. He came away with so many new skills. But he can't believe they say level 4's can do it--he was a 5 and he really struggled (he was the worst in his group He is definitely a high 5 now, thanks to the camp). Though he says it's possible that maybe if there are a group of 4s they'd go together and do less gnarly stuff? (He is sitting right here telling me this). He says to watch the videos the W-B site has of the class. Okay, now he is saying if you are a completely fearless and fast 4 and just want some instruction on gnarly stuff, that might be okay. But they did steeps in complete whiteout conditions--it didn't matter for the class what conditions are like, they did the hardest stuff no matter what. Even though he gained a ton of skills from it last year on our last trip when he was considering it, he decided to do a Max 4 group instead--he didn't know if he quite felt up to doing EC again. Oh and he had 4 + teacher in his group, which was the size of all the groups. Also, with EC you do apres, which you don't with Max 4.
As for the difference between EC and a Max 4 group of the same ability, apparently they did stuff in EC that the instructor said would get him fired if he were teaching a Max 4 group. Apparently, the Max 4 groups are more about tecnique, rather than just doing really hard stuff. In his Max 4 this year, which was for level 5s, they did a lot of black diamonds and they focused on technique, but they didn't do any double blacks, super hard trees or steeps, etc.