I've mained fire since launch. I have the helm, wrist, chest, and neck legendaries, but I would like to try frost. Realistically, how far behind would I be on my mage if I specced frost compared to someone with a frost main? Would making an alt mage for frost and praying for good RNG be better?
The only reason you are behind as a new frost mage against one who is maining it is that he might have 54 traits while you may not. Frost legendaries do play a certain factor, but not as game changing as in fire spec. Since you have good fire legendaries, it's much more worth to just change to Frost, since you got the ST and AoE BiS ones for fire (wrists n helm respectively).