Finding specific topics is sometimes tricky in the Forum, as there is so much in it! So in case it did not appear in your searches, you might find this interesting:
More in general, and after doing more (short and long) dysgu.cymraeg classes since then, I have to say that I can confirm my impression:
the two methods (SSiW and traditional classes) are so different that you can’t really put them side by side and find exact correspondences between them.
I think the best approach it a mix of self-assessment (I can think of a few questions that can help, based on my experience and other learners’ I met through the years - if you like), and just…jumping in and try courses: there’s plenty of one day/weekend long dysgu cymraeg courses, often even free that you can join at different levels and just try a few and choose the one which suits you best!