28-300 VR vs. 24-85VR + 70-300 VR

I travel a lot and have used the 18-200 DX VR lens up to now on my D70.  I am planning to buy the D600,  but not sure if I should go with the kit lens deal plus the 70-300 VR zoom for sports, or sell the kit 24-85 lens and get the 28-300.  Has anyone compared these lenses?  Thanks.