As far as Im concerned, they are not reef safe. They will sample many inverts, particularly motile ones, and possibly even some soft corals.
As mentioned, they grow enormously large too. However, it is a bit of an incorrect generalization to say tehy are all sensitive. Certain species (like orbics and tieras) can be quite hardy provide they have placid tankmates.
Being they need a ridicuklous anmount of space, I would think most reef tanks (with lots of rocks and corals) would be unsuitable homes.