I have a 220 FO. I currently have a Heniochus acuminatus in it. I lost one in QT. It appears he got caught in the input to the MJ1200. He ended up cut on his side and did not recover. The current one made it fine and is now with teh rest of the fish.
Today, I picked up 3 Chaetodon semilarvatus. These were received at the local LFS where they held them to ensure they were eating.
Other than longnose, pyramid and copperband, most butterlies are not reef. There are not many FO tank owners who will collect them safe and LFS do not get many in. I found you have to be patient in order to get butterflies. However, the upside is they are relatively inexpensive in general. I have seen threadfins, teardrop and a couple others under $30. However,aome like the semi's, tinkers, kleini and declivis are over $100 ea. A butterfly tank, in my opinion is one of the most beautiful. Mine will be a mix of angels and butterflies.