Last year we went with the QSDP and it wasn't enough food for us. We eat 3 meals a day at home and we don't skip meals while we are on vacation.
We just used the credits for breakfast lunch and dinner and once they ran out we paid for the rest of our meals out of pocket.
We had some extra credits to use on meals because there were several days we weren't at Disney and we were at other parks for our lunch meal. So that gave us a few extra credits but we ended up paying OOP for the lunch at the other park so it worked out the same either way.
If you are not a big breakfast eater then the QSDP may be enough food for you. You can actually use your snack credit for a muffin or pastry from the food court and have that as breakfast if you are trying to get by without paying for any food OOP.
But to be honest with you, if you are going to have to pay OOP for one meal a day anyway and you are not big dessert eaters, you can get by cheaper just paying all your meals OOP and skipping the dining plan.
Unless you feel the need to pre-pay for your meals using a dining plan.