I would strongly recommend that you evaluate DVC solely on the basis of using your points at DVC resorts...nothing else.
Any perk we enjoy today can be taken away with the stroke of a Disney pen, and perks are constantly changing. Since we bought five years ago, many perks have been discontinued and many others (including DDP) have been added.
DDP has already been through the introduction and gutting stages Dean mentioned, so it wouldn't surprise me if it went away in the next couple of years. It was initially a lodging promotion, not a dining promotion, and Disney has many ways to promote their rooms.
Do your research carefully, and ignore perks.