Tips are not included in the DDP, which gives you a little room to not tip as much if the service is poor--that happened to us once.
Also when using the DDE, the restaurant will want to charge one credit card or accept cash from all. On our trip last week, I put the DDE charges on my card and kept a little tally of all meals. At the end of the week, each person paid me for their dinners and were happy to do so because they had each saved 20%.
After figuring in tax and the 18% automatic tip for DDE, the price owed me for meals was very very close to the listed price on the menu.
So, I'm that neurotic that I came up with a spreadsheet and factored in all the costs of our TS meals (less discount) and an average of $40/day for CS meals/snacks. Assuming that tax is included... we will save about $140 doing DDP (yes, I included adding tip to DDP) instead of DDE.
Plus we'll have more food included due to snacks and an extra CS meal that we would not have otherwise had... both boys generally share a CS meal at lunch, so that will give us an extra CS meal for breakfast/extra days/etc.
If we weren't doing so many character buffet meals, it might have been cheaper with DDE, but right now the boys the character meals... and so do we!
I'm pretty sure DDE is not available for those. We haven't had DDE for the past year, but I don't recall ever seeing those dinners as being listed.
Don't forget, DDE is not available to everyone. You have to be either a Florida resident, OR you have to have an Annual Pass. DDP on the other hand is available if you're staying at a DVC resort on points. You do not have to have an Annual Pass.
I think Bill is right. In fact, there is at least one of our frequent posters who uses DDP only during the holidays, and specifically because DDP is accepted for the CP dinner packages.