You mention you are going May 29th to June 6th. The free dining plan is for arrivals June 27th/28th, some July/Aug/Sep dates. The kid's free dining plan is the one I see available for your nights (and the Sun & Fun offer). So no, not a good deal for you.
If there is another offer that I am missing that does include everyone -
It would be $80 more per person for the PH so that is $320. It's true that the free dining is a good deal for some but if you have to pay for something you do not want (the PHs) then I don't see it as such a good discount.
Where are you planning on staying? Values and moderates get the cs meal plan. Deluxes get the
DDP . You can upgrade from QSDP to DDP but that is eating away at the discount. Are you planning on character/buffet/family style meals? I think those are the best value for the DDP - especially for kids.
Personally I would get it if I was already planning on getting the PHs and there was no other discount available. I get discounted tickets and hotel room through 3rd party vendors and buy discounted Disney cards for food. Math is not my friend but I make sure to do it when it comes to Disney planning