Hi Abacus.
When I rang Wersi for a demo DVD/CD at the back end of last year they sent me a full CD by Stephan Weiler called The Solitaire. It's very good and he is playing on the Scala organ.
I'm not sure what OAS is in use and the CD doesn't have a date on it but it sounds impressive enough to me. He's a very good player, German/Austrian I guess with the name.