sudokuwiki's rating is based on summing scores for each step (a little more complicated than Hodoku's rating, which just gives a fixed score for each technique, the number of eliminations is factored in somehow and maybe some other stuff). It's somewhat useful for the sort of puzzle you might see in a newspaper, but practically arbitrary otherwise. Fish steps in particular get super inflated ratings; this puzzle (which just needs basics and fish) is the highest rating I'm aware of (2257):
http://forum.enjoysudoku.com/the-final-countdown-2-t38801.html (Unlike Hodoku, if it can't solve it with supported logical steps it won't rate it, so at least you don't get the crazy "how many brute force steps did it use for this particular morph" ratings.)
408 is pretty hard, if there aren't fish inflating it.