I have had both in a mixed reef in the past and they didn't touch my LPS, although I did keep mostly frogspawn, Torches, etc. They will nip at SPS, however if the coral is healthy it can survive a few nips. I would chance either in your reef as their beauty makes up for the possibility of coral damage. Both needs a lengthy QT and must be treated for fluke and internal parasites. Getting both as juvi makes it a bit easier to get them to adapt to captive life and feeding. Try to avoid the larger 4"+ Goldflakes. There are a few of us on the board that have had the larger GFs mysteriously die after doing well for months. Good luck with whatever you choose. BTW, I am a big proponent of getting the GF direct from a wholesaler in HI, as to avoid the normal wholesale chain. You avoid exposing the fish to more parasites and disease.