Hi Bem,
I would personally avoid any of the types of couplers you mentioned. The sharp edges will result in cable break as the edges will eventually cut through the cable. The steel versions are worse still and they always seem to break at the most inconvenient time.
The Sullivan type I mentioned in my previous post are gentle on the cable because of the rounded shape resulting in very little cable wear over time. They look neat when done properly.
Here is a picture of my setup.
