I just got a small one (probably a little bigger than a half dollar). He is a fantastic fish. Eats Mysis, Emerald Entree, and live blackworms which I suggest everyone try for their fish. He will hover over coral and look at them but doesn't pick at anything. I don't have any Aptasia so I can't comment on that.
These fish, every single CBB, has a unique personality so it's going to be a complete hit or miss with them removing Aptasia. They could in one tank, get traded, and not touch it in another.