We personally don't do the dining plan because we don't like being tied down for the meals. We make a few ADRs for the trip and that's all. However, there are many people here who love the dining plan.
I would definately do the Advanced Dining Reservations (ADR) if you have a certain place you want to eat... sometimes it is hard to think about what park you will be in and coordinate your ADR's accordingly but it is worth it. Also when you get to Disney and you change your mind about a reservation you can call and cancel with no problem. I love your EMH idea~ Emergency Medical Hologram!! Glad to know there are other Trekkies out there! Did you find out about the EMH?