[VladTheImpalor]

Good question, and one I'd like to see discussed more too. From my point of you, your point "a)" is the one I never choose. In my opinion, one could rarely write something for that audience which might be novel to them. Perhaps I'm just not that smart, but to me, when I picture the true masters in my field, I rarely need to communicate anything to them that they haven't figured out for themselves already, and in the rare case that I might, those types of people don't mind a bit of revisiting of the fundamentals anyway.

My favourite type of writing is one that also comes in handy to myself a couple of years down the line, which inevitably involves a modicum of handholding and starting from some fundamentals. So I'd say most of the articles should be b) or c).