I think it depends if you are talking about the top 2 or 3 kids or depth. When you get into the top 2 kids or so I would imagine there is a good amount of balance since every class has its tough kids. When you talk about depth, such as getting into the 5th, 6th, 7th, etc. place kids. you may be able to say that class 4 is a toughest. I think really that argument could only be made once you start getting outside the top three or four in a class.