I am thinking of downgrading from my AFS 70-200 2.8 VR (1st version) to something more affordable and lighter. Currently shooting DX, but who knows how quickly Nikon will introduce an FX camera that I would want, so I need to keep options open if possible. The only Nikon brand alternative I found is the AFS 70-300 f4.5-5.6 VR. Beyond the obvious 2-stop loss in light and more solid feel, I am wondering what I might be missing. Focus speed is pretty important to me, btw. Recently, I did some hand-held bird photography, and found that focussing speed was very important. On the otherhand, f8 seemed adequate for background separation at 200mm. Although I do lots other than wildlife photography, this is all that I've really used the 70-200 for. Thank you for input, and I hope no one is offended by the comparison between these two lenses. If you have any alternatives, please do share.