I have had a long nose butterfly and copperband. I had the shorter nose of the two long nose butterflies. I got it from Pyrojon who had it in captivity for a while before trying clams. It ate clams, so i adopted it. It lived a long, reef safe, healthy life until i had power failure on my vacation. He was a great fish, he taught my stuborn foxface to eat flake. I never had issues and i had everything except clams.
The copperband was from AA, it was there a few months hiding after a trade in before i bought him. He was great- never had issues even with a clam. He did eat featherdusters like mad though. He lived a long time until i moved out and he didn't get fed as often and disappeared.
The key - as with most animals- is to get a healthy one. A freshly shipped one will more likely do poorly than the ones already in tanks.
I know someone who wanted the longer nosed butterfly, tried many times but they kept dying after a few weeks. She then got one that lasted a few months... Mine had lived over 5 years, so it can be done.