Aside from providing an indication that your potential hook up failed, I can't see what these rigs offer that a standard D rig doesn't.

ok thats fine you just have to live with that...but others who maybe looking..d-rig..same apart from the bait wont seperate from a d-rig at its most critical point hopefully preventing a rebound and a dislodging of the hook in the bounce of motion on double blow out created by big lunking lazy rig sitters wink!..this just maybe the ticket..
the test rig is there to help you get the idea before courage and confidence to grasp to the next step..T-rig

I wish you the best of luck with it. However, I get the impression that you're crediting carp with intelligence that they do not have

the first carp that blows a rig out very hard without panicking as a chance of loosing the hook in the motion of speed and power versus the physics of the speed and power thats accellerated on the rebound by the orbiting bait..its not intentional at first obviously...it maybe that its safer by far after time..then if young`ns see em do this then its passed on surely ...obviously not from lake to lake..but i thought that bit would be obvious..but even there i`m proved wrong ..its just the physics by chance... bit like watercraft in carping..how do you increase your chances