Are Middle Distance Events the Most Difficult?

Last weekend I heard an athlete make an argument that the 400m and 800m were the most difficult.  Part of the argument consisted of the statement "you remember their names." I got to YOU remember their names?  If not, here are the top 500 All-Time Middle Distance Athletes from Alabama!

BOYS: 400m  |  800m
GIRLS: 400m  |  800m

*Performances in the MileSplit Database.