Don't know if this will be of much help, but I do know that even during the autumn, people skip the ledges and either go straight through the thickets or up the left side of the canyon so it is definitely still possible regardless of snow. Those willows (I think they are) at the bottom of the canyon are about 3-5 meters high so unless there is that much snow packed that low, there is slim chance that you are just going to be waltzing over top of them anyway. I haven't been in the winter, but I'm guessing the ledges are still the way to go if you're on the MR.
