Yes, I read that article, I'm reluctant to spend £50 on it! Especially as I already have a Chambon and side reins. I already lunge with two lines as I find that he moves forward better with the line around his bum.
The only thing I don't have is the 'feelines'. When I looked really closely at the pictures it seems as if the extra clips are very much like old leadrope clips. Next time I lunge I was thinking of using/attaching the two lines as suggested in the diagram.
I stand to be corrected by anybody who has used/owns the kit, because in theory it does look good, but I do think the price is a bit much.