I am personally not inclined to use the A/B/C/G designations as I am unsure of their veracity. Too many people claiming different stuff pertaining to different looking boats. It all may just lead to confusion as you may read one set of designation on this forum and then in other texts the same looking boats will be named with different designations. Of course, officially, PLAN is silent on designations.
What IS known is this, in my opinion:
2 base variant boats.
Up to one one-off variant boat with the smooth sail transition and possibly no hump.
Up to one one-off variant boat with the smooth sail transition and a hump that's very much protruding.
Two boats with a very smooth hump, almost unnoticeable.
Possibly one more boat with a slightly more protruding hump.
This article is among the best analysis of the class so far. Though it's two years old by now. I wouldn't be 100% sure its designations are correct either.