It does depend on your eating habits and the type of people going. Keep in mind that the plan does cover a meal, drink, and dessert. I think that probably most people wouldn't normally get a dessert eating at a quick service restaurant. I think if you use every credit on the QS plan and eat it all, you'll probably end up saving a little bit of money (I would probably be the type to use my 2 snacks for breakfast
). But if you don't get desserts, don't get the most expensive entree every time, and don't eat too many snacks, you would/could probably save money without the plan. Now the regular dining plan probably does save you a little more money if you want to eat at table service restaurants, but again it depends on what you are going to order, if you are going to sit down for lunch or dinner, where you are eating, etc....
I think the biggest benefit of the plan now (if you don't go during the free dining period that is)
is that you have all your meals paid for in advance so you don't have to stress about it on your trip.