hmmm, this one is tough... The DDP is a LOT of food. I usually have to really limit myself when I am on it so that I am actually hungry for my next meal.
With that being said... I am always hungry in the AM. I also find that I have more energy etc. when I eat a little something before going to the parks. If I were magically upgraded to concierge I think I would stop for a light breakfast. I doubt I would use afternoon snacks. I spend about 75 dollars on powerade, bottled h20 (the tap water there is NASTY!) and diet coke (we all have to feed our addictions, right?), so the drinks would be REALLY nice. The DDP is A LOT of food, even without the app. If the money is there though, why not? Splurge, it is vacation!
Remember there are other "perks" to being concierge level, such as help with vacation planning, getting ADR's, limited access to the floor you are staying on. The lounge areas are often quiet and a nice place to relax.