I've kept M. digitata, M. capricornis, Acropora yongei (green slimer) and A. millepora under PCs near the surface. Colors weren't great (green slimer went from neon green to olive), and growth was minimal for everything except the Montipora. When I upgraded my tank from 130W PC to 270W T5 the green slimer turned vivid neon green within three weeks. My experience is that PC's are enough to keep them alive, but they don't look that great with little to no growth. Anacropora, however, did great. It's pretty rare in the hobby though.