Have you considered enhancing the filtermenu to be able to build a more complex filter like one can do with tools from some competitors?
such as
http://www.telerik.com/products/silverlight/datafilter.aspx or see filter editor on
http://www.devexpress.com/Products/NET/Controls/Silverlight/Grid_Pro/filtering.xml
We have considered this and it is on our backlog. At this moment I can't commit to a time frame.
Kind Regards,
Andrew M. Flick
Product Manager, Infragistics