The tang has gotten more aggressive. I have a copperband butterfly in the tank too and now the sailfin has started to chase the butterfly on occasion.
The flame angel will still chase the sailfin even though the sailfin is twice its size.
Here is a picture from NM reef that I borrowed showing a red sea sailfin and the other type of sailfin tang. The red sea has more color as you can see in the picture. But the one we have is still reallly nice.