I consider the test done with this document
http://www.jjg.net/elements/pdf/elements.pdf as very illustrative for the fact that PDF and Reflow do not get along... the two ideas contradict each other, different paradigm to say so but some of you insist that it works with PDFs.
Well it works with the simples, text only PDFs. Complex PDFs with diagrams, tables and pictures can not be accurately or decently rendered when reflow is used.