I do use the entertainment book (our local HS sells them every year as a fund raiser...as an aside, I wonder if we're going to some of the same places...I'm a fellow nutmegger!).
I've never, ever had sub par service when using our book. I don't think anywhere we've ever eaten has added an auto tip for using it.
So...one anecdotal to another. Neither is really "proof".
Again, my completely unfounded, unproveable suspicion is that you won't see any more DDP customers "forget" to tip than OOP customers do. Not on a large enough scale to make much of a difference. Now, will the DDP customers be more memorabel? Leave more of an impression? Impact server perception That, I have no firm opinion on...just don't know.
It's my opinion based on what I've seen (just as yours is based on what you've seen). As I said previously, I can see the point. I just don't agree...which, again, I can certainly accept and agree to disagree. That's largely why I pointed it out in the first place, even though I don't agree: I think it's a valid point, even if I DON'T agree with it.
In the end, we'll have to wait and see. I'm sure if there is large scale revolt from the servers, we'll see Disney do something. The thing is: The union contract doesn't force them to do anything...so ultimately it's up to them.