I’ve been up Sill many times, but I haven’t been there in 10 years, so I can’t report on current conditions. I think it’s easier to get to Glacier notch from the Palisade Glacier, rather than from the south fork. I ran into a lot of willows and an unpleasant stream crossing when I approached from the south fork. My guidebooks rate the North Couloir as class 3, class 3-4, or class 4. If your routefinding is good, you won’t find any class 4. In fact, I once descended it and only needed my hands for one move. Of course, snow can make things more “interesting.” My guess is that you’ll climb the rock with hands and bare boots, stepping on reasonably firm snow part of the time. Maybe somebody will chime in with more recent information. I’m thinking about going up again in August.