Me personally, I am not nor will I ever be a morning person. The am EMH has never been an option for me. Everytime we've gone, I always say, "let's do it", but never quite make it out of bed (I've never made it to a park opening either)! I'm beyond thrilled with the pm EMH idea!! Besides the fact that the pm is 3 hrs and the am is only 1, the thought of spending more time in the parks after dark is just delightful to me (I am such a night owl)! But either way, since the EMH is limited to resort guests, it's still gonna be much less crowded than the regular hours!
Good luck on planning and I hope you have a wonderful trip whatever you decide!!