hi I'm looking into buying a 70-200 sigma lens and found these two options. If anyone here could tell me if it's worth the extra $100 to buy the macro lens? I don't shoot macro but I shoot allot of sports with my nikon 55-200 VR. So af speed is important to me, so if you know of any difference and could tell me that would be great! 579306 Sigma 70-200 2.8 Dg Mcro Hsm Ii F/nkafd www.keh.com/Product-Details/1/NA09999043586J/NA09/FE.aspx thanks!