
All foods are good if they are meeting the nutritional requirements of your dogs which yours seems to be. My understanding of physiology is that you cannot make a super being by going above meeting all nutritional requirement, once that is met it is just down to genes and staying out of accidentals :)
I don't see that price necessarily reflects whether those needs are met. I have said this before :) the man eating brisket, peas and apples is every bit as healthy as the man eating steak, asparagus and mangoes and may very well be preferring it!