I've never seen one of those either... the only advantage I see is that you don't have to keep up with the pin, but it might be a bit more fiddly to line up in the receiver. With the normal one, you can "eyeball" the alignment, push on the pin and wiggle the ball mount a bit until the pin slides home. This looks like you'd have to be fiddling with the key to push the pins out while you're trying to adjust the position of the ball mount so those pins can pop out into the holes in the receiver.
Looks like a complex solution to a simple problem.
Il Carriaggio — 1975 Argosy 24 | Il Progetto — 1976 Argosy 28 Center Bath | WBCCI# 15566
He has all of the virtues I dislike and none of the vices I admire. — Sir Winston Churchill