Yes, take advantage of it! I found MGM and Animal Kingdom to be the best parks for the morning hours. What I do is at MGM, I can get 3-4 rides on RnRc & ToT and at AK I can get at least 2 on Everest, 1 on dinosaur, and fit in It's Tough to be a Bug. But that's just me and my family, you might have different ride/attraction choices.
I found Magic Kingdom to be the worst morning EMH. Just because all the rides/attractions aren't open, and it's only an extra hour in the morning. By the time that hour is up, it gets busy QUICK! Magic Kingdom is the best at night for th EMH. Some nights we ride Splash Mountain 3-4 times without having go exit our log.
Epcot is alright for the EMH mornings. Soarin' and Test Track form a line quickly, even with the EMH. And again, since it's only an hour before the park opens, you can't get too much done and the park fills up very quick. But I think Epcot offers better EMH's for the mornings rather than night, because every time I've been there at night with the EMH it's still crazy! Although last week Soarin' was 45 minutes, so that's not bad.
And, this all depends on what time of the year you are going. But I say you should definitely take advantage of the EMH! Have fun!