Not invert safe, might be prone to nipping a few corals here and there. The main problem with a longhorn, is they get over 7" in no time, and reach over a foot in length. I find the poision release to be much more myth then fact...
I have had mine for a year in my reef. It has never messed with any coral or inverts. I have only read a couple of documented instances of them releasing toxin even with death. The biggest problem is the size they can get around 20". Mine has been a great addition and very personable.
yeah, my lfs had one get picked on my a gramma and died in the tank,, no toxin relase ,, and a cool looking fosh to boot, but the size factor of most fish is the biggest problem.
i had one in my fish only tank. he did fine for a while, but after 6 months several fish start picking at him and eventually killed him. One problem is their bio load they can put on a tank as they can foul them quicker as they get bigger