Pure Content?
Mark Pilgrim sums up my thoughts on the utility of pure content:
I wrote Dive Into Python in DocBook XML, and I maintain a set of XSLT scripts to convert the raw XML into HTML, PDF, Word, HTMLHelp, and plain text. Actually, my scripts are just customizations of larger, more complex scripts maintained by Norman Walsh. Overall, I’ve spent more time maintaining those scripts that I have writing the book. But my content is pure! Was it worth it? No, not really. Mostly I ended up using HTML as an intermediate format anyway, so a semantic HTML source document and a few well-placed regular expressions would have served my purposes just as well. In fact, this is what I did to produce the PDF version of Dive Into Accessibility.
Ironically, I was just looking at his Dive Into Python as an example of a successful use of single-sourcing from DocBook and concluded that it was a lot of extra work for few real advantages over LaTeX. I’m still looking for a good format for single-sourcing. Both LaTeX and FrameMaker have worked well for me, but to get good results I have to use a restricted feature set and write scripts to post-process the output.