If u getting flame hog, do introduce last as it can be aggressive also. Anyway, there is always exception and miracle. Personally, I think no problem in keeping tangs as long as u get a small one and feed it "just nice" and yr tang should not overgrown too fast. As mentioned, clown tang is hard to get it feeding, small one might be even harder. Personally experience is getting big fish in yr tank may stress and keep those small, timid and shy fishes stress and die. . Knowledge gathered from material may not be 100 % true, good to gather and learn from those experienced reefers, there are reefers who don't follow the norm but were successful. All the best.