We are doing the QSDP for the first time this May. We have done the Basic plan (back when it included appetizer and tip), and it was just too much food and too much scheduling for us.
We have always found the QS portions to be more than enough, and plan to share as often as possible so we can get some breakfast out of it as well. We are also planning to 'eat our way around' World Showcase, trying food from different countries. We are looking forward to eating when we're hungry and not when we have an ADR!
I have read on some threads that you can get water as a drink and fruit for dessert at most places, and some CMs will even give an extra drink instead of dessert. We still think it is a great value for us, even if we don't order dessert and here's why - I am the type of person who ALWAYS checks prices before ordering. I will get something that I don't necessarily want the most, just because it is less expensive. Any dining plan takes this out of the equation for me, because I order what I want to eat and don't pay attention to prices. For me it is not about squeezing every last cent I can out of the plan, it is about the freedom that the plan gives me. Maybe it is a mental thing, but it works for us.
I would suggest looking at QS menus and pricing out what you think you would eat, then looking at those totals vs DP totals. I priced ours without dessert, and still think we'll come out a little ahead, especially with the snacks and mugs. There are lots of breakfast items you can get with Snack credits, so we anticipate not really needing to bring extra food for breakfast.
The best QS place for us was Wolfgang Puck Express. The food was great!!

We also liked POP food court, because we could get lots of different things, and we found the food to be pretty good. Not gourmet, of course, but better than average fast food. We are planning to try Pepper Market this time for a little variety.