First off were allowed to Hunt with a Scope on our MLers during our ML Season, so I noramlly just use the Scope for My Shots. I do however have High Base See Thru Scope Mounts so I can use my Open sights if needed in a Pinch. If it's really Snowing and My Scope is full of Snow I'll use My Open Sights but normally only out to say 50 yards.
I also never would tale a shot off hand at 100yds with Open Sights, I Always use a rest, Period. The only time I wont use a rest with Open Sights is if the shot is 50yds or under and it's because My Scope is either full of Snow or Fogged over.
I would be lost without the use of being able to use a Scope. Years back when we could'nt use a Scope during our ML Season and I had to use Open Sights again I only would take a Off Hand Shot out to 50yds+- any thing further I made sure I had a good solid rest or I would'nt take the shot.