And how many times does that actually happen? I have a lot of experiance using winches and cranes, all with steel cable, and have never experianced a catastrophic failure of the cable. I've broken chains, bents hooks, etc, but I have never had a cable completely fail. Kinks and damage, but never a total failure. IMHO cable is far more durable and reliable. I have far less experiance with the synthetic line and yet have seen total failure at least 5 times.
If I had a competition buggy where weight was important, where the terrain was more predictable, and where I could afford to replace the line on a regular basis I would run it. On my personal rig where I plan on that line potentially lasting me years and I have no idea when/where I'll be using the winch and what kind of rocks, trees, or even body pieces I may have to drag the line over I'll stick with the steel cable.