If you are not staying at a WDW Resort, you cannot attend AM EMH.
And, if you cannot attend AM EMH, you should avoid going to the AM EMH park on that day.
By the time you can enter, that park will already be busy.
Yep, for that reason, I think EMH days are *good* and the sites that recommend otherwise are missing the boat. Look at that reasoning right there...
"If you are not staying at a WDW Resort, you cannot attend AM EMH".
Bam. If you are offsite, there is absolutely no reason to pick the one EMH day to go to the parks. You will not get any good rope drop time because the resort guests will be there already in lines. Thus,
offsiters absolutely should avoid this day... and the corollary to that, is
onsiters should absolutely do them. Because there will be fewer offsiters going here. What's the bigger effect... the few onsiters who get up at 7am to get in line so early on vacation, or the thousands upon thousands of offsiters who are aware if they go the day before or the day after they can have a better rope drop.
To be staying onsite and not utilize this is throwing away the best hour you will have all trip. To go the following day, you'll not only miss out on the bonus hour, but have a rope drop that is compounded by all the offsiters who are going this day because they avoided the EMH day. So your rope drop on the day before or after will be that much worse.
So "avoid EMH" is bad advice in my opinion. Unless you're talking to an offsiter, in which case it's sound.