I’m currently writing a basic XSL training course which I’ll give the first time later this month. I decided to write the training materials using DocBook 5. Lots of XML examples, lots of SVG illustrations painted in Inkscape. I used the DocBook editing capability of my OxygenXML editor. Finally, I’ve customized the DocBook XSL stylesheets a bit, added syntax highlighting using XSLTHL and used Apache FOP (SVN Trunk) to create the PDF.
I must say: it was simply fun to work with this setup. DocBook is well documented. The documentation always had an option for all of my wishes. No wasted time, no crashes, no despair (I pity those who do this with MS Word). I can only recommend to do any larger documentation work like this.