The only other thought that came to mind besides the fact that to me, most anything cooked over a wood fired grill tastes better was that if this gets too popular in today's world? I would actually start to fear for the trees. Especially if McDonald's adopted this kind of cooking.
We have a wood fired pizza oven and it is a joy to cook in it. You have full view of how everything is cooking. And the flavor cannot be replicated any other way. So I think this is a great trend and idea.
As to Tom's concern, in our case at least, all the wood we use comes from our property. We cut down a number of Alder in our renovation and I use those plus trimmings from our tree. That aspect feels good too .