Almost every holiday in proper waves I break a leash (or 2), and every time its on the swivel.
Because of that I really like the Ocean & Earth One without a swivel :)
http://www.oceanearth.com/oe/index.php?option=com_content&view=article&id=359&Itemid=267Bought one, crashed a couple of times in november at Fuerteventura in good double overhead and got worked well but the leash is still doing fine.
An option one of the guys of Dakine wrote me when I requested them about a big wave sup leash is to braid 3 thinner leashes and fix them in a D-ring the kiters use and stitch that heavy duty to one ankle leash (knee was not a good idea, too much risk on tendondamage)
Till now i did not make one because the O&A is doing fine but it is something to keep in mind.