I think our dogs are horrobly healthy, but if you insist, I will try the better stuff when summer gets here, and I am outdoors and can examine the "results" on a regular basis.
When our dog was a pup, 11 years ago, the vet said that most brand name dog foods were basically the same. He said that if the dog likes it, and it isnt like 100% styrofoam, it is probably OK.