Not what you asked, but UNESCO's recent leaflet is rather nice and has a dozen pages on impact. http://www.unesco.de/fileadmin/medien/Dokumente/Kommunikation/Open_Content_A...

James Heilman, 02/12/2014 21:20:

We would welcome sharing with us some evidence-based research on how licensing works under the Creative Commons attribution licence has made an impact in the area of scientific, technical and medical publishing.

What sort of impact? Even the most negative found an impact on citations http://ssrn.com/abstract=2269040 but am.ascb.org/dora/

Nemo