Jay,
One advantage to the current knot system is that it doesn't cause any  damage 
to the gel coat or standing rigging. Just something to think about. I  looked 
at my current system several years ago and decided that it worked fine,  
hardly ever hung up and didn't scratch or tear anything up. Having shackles  
banging around didn't seem like a smart thing to me. Let me know if you come up  
with something better.
 
Rummy