It depends upon your shooting style, but for me the critical difference may be in DOF. I like to manage (or limit) DOF carefully, and the 85 looks more promising in that regard. We're shooting Nikon with D2X bodies, and most of the time we use their 35-70mm f/2.8. It spends most of its life at the 70mm end, but the zoom is handy when accomodating small spaces or groups. That might be the circumstance for you as well, so don't discount the potential service from a high-end zoom shorter than your 70-200.