4WD safety is guaranteed more by the way you drive than by the fact that your vehicle is equipped with it. As safety officials have pointed out, when you have 4WD and a skid, instead of two wheels driving you into the skid, you have four. Four-wheel-drive works best when you slow down to allow for driving conditions, as 4WD does not guarantee safety. Indeed, 4WD will pull your vehicle out of snowdrifts, but it does not make it safer to drive. Driving for the weather guarantees your safety. For example, allowing a full two-second interval between your vehicle and the one ahead means you have ample time to stop if a problem develops.
For more info, see What are the Safest Cars to Drive Depending on Terrain