Each mega mage item has 10 base damage, 10 additional armor, and 8 M/s. The damage increase makes up for the Crit loss (40 damage per shot with a weapon and since it's base damage add 40 to each of your skills as well for the wand set). The Hit% doesn't matter. An Int mage will have nearly 100% Hit from attributed alone by level 55. Finally the armor increase is pretty enormous