we use ArcGIS Server 9.3.1 and in the near Future 10.1. Is it possible to upgrade the Silverlight API to Version 3.1 although using 9.3.1 Server? I know i wont be able to usw every Feature but are there any other problems?
Yes you can do it. New API versions are compatible with previous server versions but obviously you can't take advantage of the new server functionalities.
