I use it in my SPS dominated reef and so does a friend of mine. It's great stuff and it's not expenxive. A little goes a long way! The little SPS polyps seem to love the food. GSP will eat the crap out of it also. It's also good for all the filter feeders in your reef.
It's just another thing i feed the tank, it's good to add variety.
I was a bit hesitant to use it - seems like freeze-drying would not really preserve all of the nutritional value that maybe frozen food would have. Anyway, truth is when I feed it most everything in the tank seems to go crazy for it. I've noticed the little hitchhikers which we often ignore or overlook love it, especially the worms (peanut, spaghetti, bristle, etc.).