For example, think of generating a couple hundred PDF spec sheets for products out of a database.

I think XML to PDF is a good approach to that. I've done that with XSLT and FO ("Formatting Objects"), using Resin and Apaches FOP. The W3 specs for FO are exactly what you need when formatting for print, but unfortunately some essentials are not supported by the current FOP implementation. So it's still impossible to make your PDFs look really good with FOP. I don't know about the alternatives in perl, but I'd rather help improving existing tools, than trying to develop another incomplete solution from scratch.

^~Django