If you go in Sept., don't base your ressie off of the Fantasmic package. We always go without the package b/c Fantasmic never is crowded in Sept. and it is not worth have to endure the pre-fix dinner menus and waste the variety that the free dining plan can offer at MM & BD.
We ate at MM 2 years ago. The food was just so-so. Not anything more impressive than the frozen garbage Olive Garden serves up and then just nukes. Pretty much just glorified Chef Boyardee. Our server was horrible. He kept insisting we had to order from the Fantasmic package menu, when we did not even have the package reservation. Finally, our bill was messed up anyway.
In all honesty, I agree that Brown Derby and 50's PT are the only places worth your time. We'll see about HV.
If you are set on trying H&V because you want to give it a try, go for it. If it is just because of the Fantasmic package, put your dining credits to better use and try 50's PT.