Right now Calzaghe would win, but he would have a harder time generating an offense than most think. Awhile ago like when Hopkins fought Trinidad he would have beating Calzaghe simply because Calzaghe has some technical flaws that he can take advantage of... hell even early in his career Hopkins took advantage of some of RJJ's flaws, and he was much better than Calzaghe at doing similar things, and much more unorthodox in his fighting style.