Havoc, it seems like you’ve got all the bases covered here. Definitely I would want to make sure subscribers are comfortable with whatever connection system is in place. I would love it if businesses displayed TIdelift badges, similar to they way they proudly display their buildings’ Energy Star ratings.
Just to comment on a few of your categories, I am not thinking in terms of reference customers at all. And I have no expectations that subscribers would regularly turn into contributors. I see the two modes of engagement as very different.