My experiences with them is that they do not bother any coral. As Saltyfilmfolk said it pokes his bubble coral but doesn't do any harm. The biggest concern would be clams and wells/trachy types. I have them in my home tanks, the coral tanks at the store where I work and in tanks that the store maintains. They are usually good, but to be fair there is some risk.
They are hardy once they eat. The biggest problem is getting them to initially eat when they come into the retail market prior to customer purchase. Usually once they are eating they can easily be transitioned to other foods. We use live black worms to trigger feeding response and then ween them onto Larry's Frozen Foods. As a hobbyist I would probably just buy one from a store after they show me it eating frozen food.
