i read they're good to remove algae, however they may also eat the top layer of leathers and damage soft corals.....i haven't had any problems since i discovered it last week, but i wouldn't want to take a chance.
I have hundreds and hundreds of limpets in my tank and they have never touched any of my leathers or other soft corals. However, they do eat the diatoms and microalgae. I was absolutely delighted when they started appearing and would never remove them.
My opinion.