Aside from the hyperthreading, and bragging rights of owning the "flagship" model. Really, what the justification for shelling out the extra $100?
http://ark.intel.com/compare/52206,53445,53446,64844,53448,52207,52224,53450,53452,64843,56858,52209,52210,52212,53456,54647,52229,54619,50072,65647,54620,60636,52211,55446,52208,52215
http://ark.intel.com/compare/52206,53445,53446,64844,53448,52207,52224,53450,53452,64843,56858,52209,52210,52212,53456,54647,52229,54619,50072,65647,54620,60636,52211,55446,52208,52215