Yes, you can. With the new changes, the plans must be paid for when they are added to the reservation, but can be added as late as 48 hours before check in (if someone wants to delay having to pay for it).
We have done the QSDP and enjoy it. For most of my family it is worth it in terms of giving us a lot of food.
However, we also found that we are getting a value for items we probably would not purchase anyway. For example, we get dessert at both lunch and dinner and several ended up in the trash the last day because we just never ate them.
We also enjoy doing 1 or 2 TS meals while we are there so our last few years, we have done a split stay to get both, QSDP and
DDP.
Next summer, I think we are just going OOP. We like doing our TS meal at lunch (breaks up the heat of the day and it gives me a long time to work off the full feeling). Given that some of our favorite restaurants offer a
DVC or AP discount for lunch Monday through Friday, we figure we can use that to save.
But, the QSDP is a nice way to control costs as you know going in what you will be spending. I can say that between the meals and snacks, we were able to use it to cover all of our eating.