Although I've never personally seen it, folks have posted of the rare occasion when a synthetic line whiplashed. As far as gloves: There are still pinch points, such as at the shackle when bringing the line taut in preparation for a pull. I encourage using the same practices regardless of winchline material. It won't hurt to be safer. :-)

 

My apologies to the OP, in my copy/paste I lost my response (Although there is nothing different than Mark said). Luckily I am usually winching something else besides the vehicle so I can point it for a straight pull or use a pulley to make it straight. However, if I do go sideways I may only get five or so feet before I need to stop and redo it.