I think Zero Off and the more powerful engines coupled with the boats being bigger, thus not moving due to skier load, is a contributing factor to alot of injuries. If you don't have your technique together when you go against the ZO, be prepared for the pain dished out. I think alot of folks need to slow the speed down, get some coaching and really get their techniques down pat before they start pushing with the shorter lines. Get to where you ski in control and you will progress much faster and hopefully without injuries.