I have a red ORA Goni, and I've never seen the long sweeper tentacles that you might see from chalices, brains etc. I have seen tiny little bluish projections coming from to polyps from time to time, but not sure if these are stingers.
But the Goni has never hurt a nearby montipora or plate coral, so I've always considered them rather benign. But am really not sure what they're capable of in the right (wrong?) situation. But I'd be more worried about an aggressive coral with a long reach hurting the Goni than the other way around. I'd keep known aggressors away from it and have a few inches at least of free space surrounding it. I'd also make sure the polyps don't make contact with anything else, including live rock. I've found it to be one of my favorite corals and very easy to keep.
