I have recently been in contact with a guy that has 3moorish idols in his ''reef pool'',he has had them for ~3years,and i asked what the ''secret'' to keeping them Fat and healthy is,His answer was lots of swimming room and natural food source,he has alot of sponges growing all over the place and they do eat flakes/pellets/some blood worms.I think in my 5ft tank,a single moorish idol might not be too happy for long-term unless it's super tiny.They DO nip at zoas,lps and HAIRY SPS.But in his 8ftx4ft x1ft tub,all his corals are mature and their ''nipping'' is harmless.This is the only real insight i have on these wonderful fish.In my opinion,i think we here as dedicated hobbyists might have a better chance at keeping one alive longer than a joe-schmoe that walks into a LFS and buys it cause it looks cool.Just my $.02.
