This is just a feeler here... Since adding the 500 I haven't touched the 300/2.8. I feel like I have abandoned an old friend. The 300/2.8 is the staple lens for most and I have one sitting unused. (insert all the "send it to me" jokes) Most of my work is of wildlife. Mid to large birds for the most part, small birds for fun. The 500 is a great piece. I have none of the acquisition problems I thought I would have, it seems to be plenty fast, and although I have modified my TC's to AF on the 500, I have yet to use either of them. I still have and use my Sigma 70-200/2.8 and it responds very very well to the 1.4 APO EX DG TC, netting me 280/4.0... that's almost 300/4.0. The 500 is a commitment I am up to. You don't take this lens walkabout. The Sigma is about the same size and weight as the Nikon 200-400VR, and though a third stop slower and no VR I don't miss what I haven't had. So someone tell me I am nuts to be considering ditching the 300 and the 500 in favor of a 200-400VR, paired with the 70-200 + TC. Are we ever happy?? Where does it end?