I have implemented a report in standard WPF controls and have also implemented a DocumentPaginator to take these controls and convert them into a document for p
DocumentPaginator
If a commercial SDK would be an option, there is one company I came across that has a professional XPS to PDF conversion option (and more).
http://www.nixps.com
Warning: I'm not affiliated with this company nor have I tried their products. I have on the other hand heard good things about them.