I sit down every trip and estimate the approximate OOP dining expenses.
Then I take a look at the DDP costs. If we have or are planning to get an AP, I compare that to the savings we'd have with the DDE card.
So far, the DDP has not been a savings for us, not even close to break even.
It depends on how you eat. We don't eat desert, we don't drink pop, we usually eat lower on the value scale - chicken or vegetarian dishes. We also often eat two table service meals each day, so we'd be loosing the CS credits.
I also don't go to Disney to focus on eating and I'm the kind of person that would stress about using the credits, skipping ADR that made the DDP "worth" it, etc. So I'd rather skip the DDP and be free to do what I want, when I want, and save myself the whole DDP hassle.
We have had DDE on the last two trips and if anyone is going to have an AP, I definately recommend the DDE card. We saved BIG money using DDE. Last trip I was with two drinkers and take that 20% DDE discount on food PLUS two Margaritas and two Glowtinis every day, and it really adds up quickly!