It is now possible to produce a PDF direct from PROIV using the standard spooler options and an XSLFO Stylesheet. The PDF is produced using FOP which is included in the PROIV version 6 install. I noticed in the other thread concerns about the cost of third party products and licensing issues. FOP is open source so there are no license issues when deploying your reports. The only additional cost is the time spent developing the stylesheets. You will need to learn XSLFO and there are a lot of products that help you write it including some that are WYSIWYG. There are some XSLFO examples included in version 6. This topic is also covered in the new PROIV V6 training courses.
To show what is involved in creating a PDF with PROIV I have attached a document I did for somebody recently. I hope you find it useful.