Hello! Our twin boys loved bother Narcoosee's and Citrico's (they were 8 at the time). Citrico's was much quieter, but several other children there as well. I think if your son is used to that kind of environment you should be fine. Besides, they had one of the better children's activity sheets etc., so you know that Disney is planning on having kids there.
I am not sure your son will be able to order the Surf and Turf if he is on the kids
DDP. I ordered it and my son and I shared my meal and his meal (I can't eat but a bite or two of lobster). The kids' food was good enough that this was fine with me!
If you are choosing between the 2 restaurants, Narcoosies certainly has more hustle and bustle and ambiant noise. It also has the opportunity to watch the firewoarks from the deck. For comfort and peacefulness, go for Citrico's.
Either way, you should have a good meal!