A new version of FilteredPageReference has now been released which contains the following bug fixes and changes:
There was a bug when using the delegate to override allowed page type settings which has been fixed.
In previous versions if using PageTypeBuilder, all assemblies and types were scanned to find relevant page types and interfaces. You now have to specify valid assembly and full type name prefixes in the web.config, these configuration property values should be semi colon delimited. Configuration example is shown below: