I’ve wanted to report on this for a few weeks. Maybe there’s someone else in the same boat who would be interested. 
I know “value” on the dining plan can be a controversial topic, but this is our experience. We own DVC and have never purchased the dining plan, but I decided our recent split stay was a perfect opportunity to try it. Our first reservation was 2 nights, just DH and me, followed by 5 nights with our college-aged sons. So we basically had the first 3 days to use the plan. The DxDP was $119/person/night so $476 total for the two of us for 2 nights. So we had 12 TS credits and 8 snack credits, plus the 2 refillable mugs. Here’s how we spent the credits:
Dinner Cali Grill for 2 people 4 TS credits $256 (w/out tip)
Dinner Topolino’s for 2 people 4 TS credits $211 (w/out tip)
Dinner Toledo’s for 4 people 4 TS credits $340 (w/out tip)
Snacks at Epcot F&G 8 credits $60
Refillable mugs $40
The cost of everything we ate and drank on the plan would have been $907 had we paid OOP. Now of course, we likely would have ordered less expensive items in some instances, but we typically do order alcohol, appetizers and at least one dessert at dinner. We would not have purchased the refillable mugs had we not had the plan, but we did use them and obviously they were good for our entire trip. Another thing that worked out really well for us was that we brought the leftovers back to our villa and ate them the next day.
Also, full disclosure, we bought $50 worth of groceries and spent $130 on extra snacks/QS/alcohol for 3 days. ($60 of which was spent on drinks at the Gurgling Suitcase waiting for our room to be ready on check in day!)
We really wanted to eat at the Signature’s CG and Topolino’s so it was very nice to order the expensive items and not think about the cost. We ordered glasses of wine which cost over $20, which we would not have done otherwise. The best “value” was the dinner at Toledo’s (rib eye for 2 for $89) which was a 1 credit restaurant. Overall I think it was difficult to find a 1 credit “nice/adult” restaurant that has higher priced entrees (that isn’t a buffet/character meal). We had also considered The Wave, Terralina’s, and Wolfgang Puck Bar and Grill but were really happy with our meal at Toledo’s. We could have eaten at 1 credit restaurants for breakfast/lunch and dinner each day, but one TS meal a day is enough for us.
Since DH and I have started doing alot of split stays, I may try this again. I think it works really well for a 2-3 night reservation at the beginning of the trip. It does require some homework and planning if you really want to get as much value as you can. I definitely wouldn’t want that many credits for my entire stay.