Never did it with the dining plan, but we did the package the last trip and were not disappointed. We had a 4:00 sitting. Nice and early so we didn't have to worry about being late for the show. The restaurant was quiet. The food and service were excellent!
It was nice having the package because you can order whatever you want off of the menu. We don't always get appy and dessert. This way you can, even if don't eat it all, it's worth sampling....
As far as seating, I liked it. We didn't have to go an hour and a half before. I think we got there 45 mins before, a major plus with little ones. You're closer to the exit there too.
We went to Fantasmic in 2004 at "value" season and got seating in the higher seats in the second to last section. I thought for sure we weren't getting in after getting there early and wading through the masses to get a seat! Less stress the other way.
It may be worth it to pay oop for this one, especially since it's 2ts.