You should look into PrinceXML (what name do you indicate in your question, but don’t tell us that you didn’t like it), which I mentioned here a few days ago - even with screenshots showing the results. Other examples of the prince's output can also be seen.
However, what you mean by “true WYSIWYG” remains rather obscure to me.
Because you need to show me the XML visualizer first ... the one that displays your XML to me on the screen just as you expect your PDF pages to look.
Update: Here is a set of examples for PDF files created by PrinceXML. You can download 14 of them using this command on Linux or Mac OS X:
for i in 9-02 9-01 8-12 8-11 8-10 8-09 8-08 8-07 8-06 8-05 8-04 8-03 8-02 8-01; do wget \ -r \ -t 3 \ -l 1 \ -c \ -O AdvancedAquarist-200${i}.pdf \ http://www.advancedaquarist.com/pdf/AdvancedAquarist-200${i}.pdf/at_download/file done
On Windows:
for %i in (9-02 9-01 8-12 8-11 8-10 8-09 8-08 8-07 8-06 8-05 8-04 8-03 8-02 8-01) do ^ wget.exe ^ -r ^ -t 3 ^ -l 1 ^ -c ^ -O AdvancedAquarist-200%i.pdf ^ http://www.advancedaquarist.com/pdf/AdvancedAquarist-200%i.pdf/at_download/file
IMHO, rather complex layouts are presented here.
Please note that old issues of this magazine until May 2008 were created with iText 1.4.6 (in accordance with their metadata).
New releases starting in June 2008 were mainly performed using PrinceXML 6.0 (which is an issue from 4 years ago ...).
However, both applications created a very similar layout ...