Have you all considered authoring in markdown and using pandoc to generate the various output formats (html5, PDF, etc). Pandoc allows for the markdown to be extended with LaTeX as needed, and has good support for embedding generated graphics and such. I've worked on some large software projects using this technique and have had success with it. It takes some time to get it set up initially but after that, the documentation is very flexible and easy to edit.
I'd be willing to help set up a maven build for this if you all are interested in doing it this way. I agree with the others that having an ASCII based format is pretty critical for working with others. Have you looked for a WYSIWYG markdown editor? I imagine one must exist. -Andy
