there are the legal-talk and legal-general mailinglists where you can ask.

IMHO. CC-SA is ok, for Stockholm there are only 100 or so people to attribute, and max 50K for the world. And since the only way to attribute/contact people is through the Openstreetmap.org, you don’t have to save anything just refer to openstreetmap.org.

Then again there are always people that want to have things differently, E.g. IMDB was started as a collaborative, then turned commercial.