I suggest that if you upgrade to the Deluxe Dining plan only do so if you have 6 months to plan. We did the deluxe dining plan twice, once many months in advance (the first time) and the second time with just a few months notice.
The deluxe plan is only worth it, IMO, if you plan every meal at a character experience. The kids loved all the character dining experiences. And since they take reservations 6 months earlier, then you can try to get to those hard to eat places like at Cinderella's Royal table at the castle.
The second time we went I tried to make reservations but found a lot of restaurants were already booked. Still, we were able to walk into a lot of them. But the Deluxe Dining plan is a waste if you end up using counter service.
I had to create a whole spreadsheet to plan what park I would be at on which day, then made my reservations. I tried to plan around the Magic Hours whenever possible too.
The other bonus with the deluxe plan are the snacks. The included water, ice cream, etc. was a welcome treat. I barely spent another dollar on food when I used the deluxe plan.