Hmm maybe I can give you some more info in a couple days when my EK 5th ed arrives. My friend has the 4th ed.
I think I might have heard that the 5th ed. has some better diagrams or something? I honestly don't think the 5th ed. is going to get you any more points on the MCAT than the 4th ed, just like how in the end, all textbook revisions basically give you the same overall info. I could be very wrong though.