Its still 2 DDP credits I believe. The restaurants designated as signature are designated that way whether they be lunch or dinner, but most don't serve lunch.
If you are thinking of going for lunch you might want to consider paying OOP for it. That is what I will be doing. All I really want is the Cobb Salad. Obvoiusly not worth 2TS credits. I'll save my "big eatin'" with appetizer and dessert for somewhere else.