Come to think of it. If the shackle is smooth and round on the inside than you have replace the bungee past the green bead for a line and run that Through the shackle (not have the shackle attached to the ring) and thus has a very close approximation of the more conventional system. Same working but without the cost of an extra small block. You could event replace the small block and shackle for a small stainless steel ring and run both lines through that and go cheaper still. The ring must be small enough to not let the bead through.

Wouter