I think it's a little weird for a name since it's a plural word. To me it's like using Roses, Cacti, or Zephyrs as a name. It just seems strange, whereas Magus, Rose, Cactus, or Zephyr make sense to use as a name. Magi does have a nice sound though (which the singular Magus, Magos, or even Mage does not have!).