My 2 cents but I agree with jdeb. I have tons of them in 3 tanks and (maybe fortunately) I've never had an issue? A grow out tank, a non copper QT holding tank tank and my DT. Was guessing/hoping they are part of the CUC so I left them. They spend more time on the glass than my snails do. Visually maybe but I like the look on people faces when I tell them they are starfish LOL.
Take that with a grain of salt (pun intended) as I'm also a 3 year marine noob. Paulo what did you hear about them not being good ?