Good point on the different digestions... sweet feed is basically oats and molasses if I remember right, would think that'd be fine. Corn has some nutrition issues too, for deer it's largely empty calories.
"The Omnivore's Dilemma," a book by Michael Pollan, makes some really strong arguments about corn's place in our food system. His basic point is that cows aren't really set up to eat corn as their main food... but corn is cheap so that's what they get, loaded up with additives to promote growth and nutrition. He goes on to say that corn is cheap only because we have cheap oil, so when the oil market REALLY goes to hell, as it will soon, corn... and, by extension, meat and milk... will go way up in price too.