In fact, there are only a few lenses that deliver higher sharpness mounted on the Nikon D800 and even then the best performing lenses provide just 12% higher sharpness from a 30% increase in Raw file size. Given the price, this all makes the D600 look particularly attractive.
Now there's an interesting factoid for you, and from a source as empirical as DxO it's one that carries a lot of weight. Read more about that as well as which lenses from a selection of seventy perform the best on Nikon's newest generation of high-resolution sensors via the external link. The results are often about as you'd expect, but there are some real surprises in the list (such as Nikon's 24-70 and Tamron's 24-70 coming in at a draw, for example).