I will tell you from experience. Butterflies will nip your corals to death. I had a threadfin that loved my corals. Cost me alot of money. In time so will your Trigger (especially your inverts, if you have any which im sure you do in a reef set-up). If the books say "with caution" dont try it. I even had Yellow Tangs that loved my corals. Get reef safe fish only, you will be glad in the long run. And btw, I would be scared of that snowflake too.