As others have already said, it typically increases attendance. The thing to remember is that not everyone gets hoppers. So people staying at WDW with no hoppers are going to be in that park all day. This is an automatic jump in attendance. It doesn't really matter if it is morning or evening hours. If you have hoppers then you can take advantage of those extra hours by hopping to another park during the busy times. I don't really use hoppers as I have memories of losing many hours of valuable time by jumping from one park to another as a teen/young adult...haha. That said, if I did use hoppers I would probably go to a low crowd park for most of the day and hop over later when the crowds start going down to an evening EMH park. I find extra hours in the evening more beneficial than 1 in the morning. Of course, I now have 4 kids so getting them up, fed and going in the morning can be a chore ranging from 20 minutes to 2 hours! I don't count on early morning for anything.