In reply to MarkDH08: Mark - I started climbing (and working in gear shops) before Brian Hall had invented the B and C rating system, so perhaps don't think about it as much others do. I know that Hall's ideas were to give a rough guide, which it does very well and makes sense for beginners - but I don't actually know if CT or any shop that sells their products would call the Nuptses "C2" or not. Looking at other crampons that get called C2, the Nuptses are similar, but I don't think you have to take these things as complete gospel.
Personally I wouldn't worry too much about putting the Nuptses with the plastic back and front binding on any boot that is crampon compatible, such as SLs, but that's just me. Don't take advice from strange men on the internet - it can get you into all sorts of trouble!
Pick a good shop that sells them and see what the people think there for example.