I have six of these little anemones and love them. They've been a lot easier to keep than clownfish-hosting anemones. In spite of their trade name, my "rock" anemones all stay on the substrate--although they will sometimes attach to a rock nearby--and will often pull themselves completely under it at night. They did a good bit of wandering at first, but have all settled down now. They also seem to wander less if kept near each other, IME.
I've never had any problems with them harming any other livestock. Either my molly miller blenny is smart enough to avoid them, or they don't have a very powerful sting. I've also seen one of my serpent stars brush right up against one without any apparent ill effects. I'd be a little more worried about very tiny fishes like tiger gobies, though.