When we made our debut trip to WDW in summer 2001, EE (now EMH) proved to be a distinct advantage. I think it was 90 minutes early as opposed to 1-hour. I remember just zipping from attraction to attraction at MK with no waits in those opening minutes--it was awesome.
Flash ahead to summer 2003 and EMH did just about zilcho for our family. The crush of people streaming to the EMH parks was all but overwhelming from the get-go. Any early magic was gone in a heartbeat--the lines swelled quickly.
To me, it is no longer worth missing an extra hour of sleep to get EMH. This year, we are vowing no EMH parks. I forget, though, should you go to parks the day BEFORE EMH or the day AFTER EMH?