> Ok, looking at the features of Sphinx more closely now.. Since there are various people here knowledgeable about Sphinx.
> More questions..
> Does Sphinx support output to docbook? 
Not natively, but it should be possible to write a converter: https://github.com/HolgerPeters/sphinxcontrib-docbook
I think the basic process is to run sphinx with the XML builder and then transform that XML to docbook XML.
My question would be: why do this?
Is this for PDF support?
It looks like there is a builder that can be used to produce PDF output: https://github.com/brechtm/rinohtype
However, it requires Python3.3+
 
How important is PDF support? Just curious as I typically only use HTML for documentation.
 
> Does Sphinx support *configurable* HTML output? I.e. can I use my own HTML templates directly to change the output structure and style?
Yes. You can create your own theme and use that: http://www.sphinx-doc.org/en/stable/theming.html
Some existing sphinx themes: http://www.writethedocs.org/guide/tools/sphinx-themes/
 
Aaron