Steven,
there are very many SK hokei which arenot taught. For example I first learnt 2 versions of Tenchiken dai san 3 years ago - 24 years after starting SK. Most instructors teach what is in the curriculum but not all SK hokei can be found there.
The question you may ask yourself is - will I be a better kenshi if I know all Ryuo ken & sotai)? I suspect not. In fact you'll find that you know all the kihon contained in these katas. Therefore learning the katas do not help your progress significantly.
Cheers, Rob
Robert Gassin
Melbourne ShorinjiKempo Branch
Australia
"Never fight an idiot. He'll bring you down to his level and then beat you with experience"