D600 and Sigma 70-200 f/2.8 OS
Had it and sold it for the Nikon 70-200 2.8 VR ..The Siggy wasn't a bad performer, just think Nikon is a tad better!!!
I have used the Nikon VRII and it is a fine lens. But for about $1K less, the Sigma is almost as sharp in the center, and I'm actually quite impressed with how well it controls color aberrations when shot wide open. In fact, I'll go as far as saying it is better than my Nikon 85mm f/1.8G at f/2.8 in this respect. I'm mostly a hobbyist so even the Sigma was a bit of a financial stretch.