I know one guy that has one and he flat out said they are unusable for newborn lambs until early April (North Dakota).   I have found that we need wooden barns until the lambs are 3-4 weeks old, but we lamb starting Feb 5.  It's not so much the cold that bothers, but the differences in extremes.  Barns warm up in the day from the sun, and gets cold at night. 

 If you are further south or lambing in warm weather, then temps shouldn't be a problem.  One other thing, sheep will eat-destroy actually- the fabric on a hoop barn.  You will need to put up barriers to keep them away from the sides.  I saw this when I was at this guys farm.   Hope this helps.