I think I've seen Pat Parelli use a setup like that for what he calls Finesse work. He puts thin ties between the rein and the bit, and if the rider exceeds the pressure rating for the tie, it breaks. It was a really interesting demo, showing how the horse responds to minimal pressure on the reins, and I can see it as a good way to polish rein aids, but as a matter of daily use, I don't think I would use them. When I'm out on the trail miles from home the last thing I want is a tack failure, and riding out with equipment that's built to fail seems silly to me, in that type of situation. I'd try riding with them to test myself every now and again, though. I've never seen reins like that available commercially, either (although I never looked on Mr. Parelli's website for them).Has anyone used ultra light/ultra thin reins? I mean like 1/4 in of light and strong material with breakaways at the bit. What is your opinion of them?