One thing I noticed is that the coral do respond to the moonlight LED's in varying degrees. I used to have them on all night when all the other lights are out. I noticed that my zoas were not opening all at the same time. Some were open with the metal halides/T5 light, some were open when the moonlights were on. I changed it so that the monlights were on only for a few hours after the othher lights were out. Now all the coral are open together.
The moonlights offer no significant benefit to the coral. They are there just for our viewing pleasure, and because it looks so cool!