If you crowd them or do not feed them enough to grow 3+ inches in a year, they can be total asses. If you keep their needs met, then they can be just fine (just fine, not awesome)... but most people will not feed them enough in a reef to keep them happy. Feeding them enough makes then not too reef friendly.
I have had some do fine from 2 to about 7 inches with 3x a day NLS and Formula 2 pellet feedings - this happened in 18-24 months. Then, they had to move on since my 8 foot tank was not big enough for them anymore. They lived with my Chocolate, purples, yellow and black tangs and they got along.
I cannot stress enough how much food they need if they are not going to get mean. Heck, they still might get mean. I had a friend in KC have one destroy all of his Acans in about 24 hours. Most people know that tangs are not always 100% reef safe, but this one seems more risky than others.