Matthias,
One serious bug is if I have a PDF file that has fifteen pages and I import that PDF into several QuarkXPress 6.5 picture boxes.
For example, into box one I import page 1 of the PDF; into box two I import page 2 of the PDF, and so on. When I save and open the version 6.5 project in QuarkXPress 7.3, 7.31, or 8.0, all the picture boxes ...