All of my owners have heard the rant: there is absolutely NO need to feed anything other than a complete kibble to your healthy Wheaten. That "grain free" and "organic" and "human grade" and many other claims of very expensive foods are just ways to get you to pay more because you think it's better. And that they are all current fads and some time down the road, there will be a new fad.
Of course, seeing an article from a vet that agrees with me is always welcome! http://tinyurl.com/h5ach7y
But here's the important thing in the article...that if you change food to address an allergy or other problem, you are likely missing the real cause of what's wrong with your dog. And that means that your dog isn't going to get better.
So...hey, if you want to spend more money, fine. But if your dog has some sort of issue...get to the bottom of it and don't think that some sort of marketing ploy is the answer.