There's a survey at: http://www.dini.de/projekte/oa-statistik/english/
Which repository managers might be interested in completing or forwarding to their contacts to complete. It is quite a long survey, and I didn't find all the questions easy to understand. I think it's mostly aimed at scientists who are reading and writing articles, rather than repository managers themselves.
I blogged my personal perspective on the survey on my WRAP blog: http://blogs.warwick.ac.uk/wrap/entry/survey_on_open/