I wasn't on the Curves diet, but I did have the experience of trying to keep up with my new healthier lifestyle while at WDW. What happened for me was that I did great for a couple of days and then totally went crazy and ate anything I wanted at any time. The crazy part was a lot of fun, but I felt very sluggish and it took me several weeks to get back on track once I got home. So, was it worth it, in retrospect, not really. This was just my experience--your mileage may vary.
From what I understand about the Curves diet is that you are allowed a pretty high calorie limit and that it varies day to day. Maybe you could try to stick to your calorie numbers even while you eat WDW food. To help keep calories under control, try the following:
--Share whenever possible
--Always order the small size
--Drink as much water as possible
--Don't eat unnecessary side items--if you're not that crazy about fries, order just the burger or get the apple or carrots that most of the counter service places offer instead of fries. Anything at a counter service restaurant can be ordered a la carte, even if they only show it as a meal on the menu.
--Eat a good breakfast with some protien
--Get snacks from the fresh fruit stands in the park.
Hopefully you have a great time!!!
or do you keep to it strictly? 
I guess there is guilt either way.
