I like this addition to the dining plans. At my last Disney vacation I tried the DP for the first time (Im a pass holder). On one aspect, I know that financially I am paying more for the DP than I would if I just purchased the same food without it. That being said, it was a great way to budget...
5' 6'' female, 280lbs fit no problem. Also, the test seat isn't always perfect. My dad was in the "red" zone, meaning he wouldn't fit, but he fit no problem on the ride. No one in our group got kicked off, that I could tell.