maybe it's a too old thread, but here it is. I needed to convert from ePUB to PDF in a decent quality, and I landed onto this forum. The tool written by Jellby works fine and has a nice GUI, but I had troubles converting a number of ePUB files. So I modified the code (it required the Author field to be non-empty), and also added some code to remove the annoying PrinceXML annotation on the first page of the PDF. I also created a python package (by adding a setup.py script and splitting the code into library and start script). If Jellby or anyone is interested, let me know and I'll publish the code.