I know a local cop in southern Florida who has a good "working" relationship with a local, who knows and associates with a variety of drug dealers and may be one himself, however he is more valuable as a CI and they don't have anything to actually arrest him on.. anyway, this local always carries a little antique-looking Derringer as his self-protection piece. With the intent of these things to be used at little more than arm's length, I think they make a fine SD pistol. Just know the limitations; it's a gut gun not a paper-puncher, don't expect to put two mid-sternum from seven yards. He has no problems concealing it in a pocket in the Miami heat.
As a display piece or a collector item, hell, they're pretty sweet. I'd like an antique for my collection.