For the most part they are cool. Mine ate every bit of aptasia in 2 weeks. A few months later, he had eaten every feather duster, then started nipping at my clam mantles, and zoanthids.
I agree with Lonnie, great fish, and they will take care of the problem 100%. Peppermints are hit and miss. Mostly because they are often mislabeled. Retailers receive peppermints that are not actually peppermints.
I don't like the fact that CBB don't typically eat prepared foods, and waste away. They are beautiful fish, that are over collected because of this.
If you purchase one, have a backup plan. Someone who can take it once it clears the tank, and give it back when you have aptasia again. And you will.
Maybe now is an appropriate time to set up a forum for trading fish/equipment/etc...
I could use one aswell, but only for a few weeks