i think it varies class to class...for example: i believe their are 3 wrestlers at 189 5A that would win any other classification.(mamie, elliot, evans)
you are probably correct about the 4A 152 bracket being tougher then the 5 or 6A. but the best 125lb in the state is probably tyler caldwell(6a).
i dont think their is much doubt that the keller brothers would win their respective weights in 4A.
depth wise you might have a bit of a point, but personally i think the champions in 5A and 6A are a littler stronger, or at least they will be this year.