Perhaps we should ask Firefish3 if it's even going in a reef tank before dismissing the fish as "not safe"...
The "tall tank" requirement is valid though...what sized tank are we looking at...?
As far as being "hard to keep" they are not "ick magnets" or as "disease prone" as some other popular fish, but they can be hard to ship...buy one at a LFS...and they can be hard to get to eat...both the 3"-4" tall babies and the 12"+ sub adults...
Your best be would be in the 6" to 10" range...stabalized at a LFS and known (seen) to eat prepared foods...best kept singlely (from what I've seen)...
HTH