I was training on the course this past weekend. Completed Butlers Lake to Highway P, back to Butlers Lake and then south to Mauthe Lake and finally back to Butlers Lake (48 miles total). While most of the trail is good, parts of it are snow covered and the snow has frozen making it very hard and lumpy under foot. It was a lot easier running off to the side in what was about 1-2" of snow. The snow is worst in the more northerly parts above Greenbush campground which is also where the trail is the most rocky. Some sort of traction device would be very helpful (Yaktrax, screws etc.). It wasn't that cold (30's in day and 20's overnight) that 2 layers were sufficient in the day while I had to add a third in the evening. Trekking poles were essential after it got dark due to the very uneven terrain and my tiredness.
Hope this helps you prepare and good luck to everyone.