Pros: Holds the plug snugly on both ends, and the contacts inside seem to be held in place very well. Used the metal, gold-colored one because it can be opened and the contacts adjusted if necessary, but found that its ends simply pull off and push on, they don't screw on/off. The gold one, while OK, did become unreliable and after opening and re-bending the contacts about 6 times found that it's just not all that good. This one is much better. (So I got 4 after all, nothing lasts forever.)
Cons: None I can see yet.
Works very well. Holds the plugs solidly and makes good contact at all three points.