This has been an interesting topic. I have over thirty years observing experience and can relate to some of the comments but not to others. I would say that whether you call a cloud St or Sc is related to the height of the cloud and visible structure of the same. The same Sc at, say, 2500ft observed from sea level would be St 2400ft up the mountain as any hill walker would know. I've reported Cu at 7000ft and had a glider pilot tell me that he was at 9000ft and the Cu base was above him. I was always happy to report high Ac at 18000ft if I felt that to be correct.
As observers (old style!) there were endless "discussion", in any office I served at, about all aspects of observing and I always looked at these as good learning opportunities. Some offices, however, were very set in their observing ways and didn't take kindly to new ideas.
I'm intrigued at how Will can tell a cloud type when he's in it. Just hill fog, surely?