Say you wanted action shots in low light, such as a football game or auto race. Choice one is a D700 with the Sigma 70-200 HSM lens. Choice two is a D300 with Nikon 70-200 AF S lens. Which one would you choose, and why? The price difference, according to Adorama, is greater between the two lenses than the two cameras. Is that lens really worth it, or is it the brand name recognition?