I own the AF-D version of this lens that I bought used at Christmas time. I've been thinking about upgrading and have been considering the 70-200 but also the 80-200 AF-S. Recently, I realized that the AF-S version of the 80-200 isn't produced any longer. This seems strange to me. Why would Nikon create an AF-S version of this lens, then stop making it and begin to offer only the AF-D version? Is the used AF-D version I currently have (2-ring) the same as the newest version? What's up with that?