It looks kind of nice, but I'm not certain I should invest the time or just put LyX and org-mode away and finally learn LaTeX properly.
The Playing Field
What you most have to consider is:
Can I use Texinfo?
Texinfo is pretty niche and was developed with a very specific purpose, supporting only a few formats that LaTeX doesn't already support in some way or another:
- PDF via TeX
The first three formats are those used commonly by (La)TeX itself; while DVI could be considered 'niche,' PostScript and PDF are most certainly not. These formats are widely used for mass dissemination, as you've probably noticed.
The Info format is obviously very niche---it can only be effectively used from within Emacs. If you are writing a package for Emacs, however (or some other resource to made available from within), then the Info format is good for you: +1 for Texinfo. (Technically, GNU maintains a stand-alone
info program. For what it's worth.)
HTML is supported in the general case by
latex2html, a program that attempts to convert LaTeX source files into HTML pages. Texinfo's equivalent will undoubtedly tailor this to the concept of a manual, and certainly in the style that is ubiquitous in GNU manuals. If you even need this format, Texinfo is good if you want to keep the style consistent with other GNU manuals, but it necessarily cuts down on creative freedom (to the best of my knowledge). +/-1 for Texinfo? I don't know.
DocBook, an XML schema for manuals, is falling out of popularity---at least in my circles. There is still widespread support for it in entrenched systems, but (in my experience) there is always an alternative. If you do need it,
tex4ht has limited support for it. I
XML format is almost useless unless you're into that sort of thing, or you are actually storing your manual in a database somewhere. Nevertheless, the aforementioned DocBook is in fact XML, and there are plenty of tools for manipulating XML databases.
LyX, LaTeX, and
LyX is a (arguably, see comments) fine system for document management for
- those who do not wish to have a terrible amount of control over their document and for
- those who do not wish to be inescapably exposed to the organization of their document.
To my knowledge, LyX has support for neither Texinfo nor DocBook, and I would be surprised if its XML output was any good at all. (Again, XML isn't terribly useful.) If you understand LyX and know how to work with it (i.e. document structure rather than document formatting), then you've already (in my humble opinion) learned the hardest lesson of LaTeX and it would do you well to continue your education.
As for Org, it is an excellent tool for document prototyping. I mean it. I cannot emphasize this enough. Really. But as with any on the market today, Org has rather limited support for LaTeX export, and the defaults are rather ugly to override on a per-document basis. I mentioned an Org workflow in the comments but was unable to link you to exactly what I meant;
Everyday LaTeX and workflow? and
A simpleton's guide to (...)TeX workflow with emacs
are excellent resources. Org's advanced outlining capabilities coupled with its (admittedly decent) LaTeX export makes for some nice document skeletons to start working with. (If you're going to use Emacs further for this stage, please check out AUCTeX, available via
M-x list-packages or your favorite package repository.) Additionally, as I mentioned in the comments, the contributors to Org are working hard on a new exporter (coming in Org 8.0) that will feature Texinfo export. Depending on the quality of the export (which is likely to be high, since the goal of Texinfo export is to maintain the manual in its own format), you may not need to learn it in-depth. Besides, looking at your own document in Texinfo format will probably teach you leaps and bounds about the format itself.
Unless you are going to be writing manuals for Emacs packages or other GNU software with any complexity or frequency, it is my opinion that it is not worth your time to learn Texinfo, and it would almost certainly be fruitless without a firm understanding of LaTeX behind you.
If you're even looking at Texinfo, then LyX is starting to lose some of its value to you. LyX has its place, but there are far more tools that work with (La)TeX than there are that work with LyX---it's a simple matter of market saturation.
If you understand the concepts of LyX very well, then LaTeX should be simple to understand and easy to use on a just-do-it basis. I highly recommend A Not So Short Introduction to LaTeX as a starting document, and many other resources can be found littered throughout the site. Of course, if you run into any problems with TeX and friends that you can't find a solution to, you are most welcome to ask a question here; there are (again) far more experts in TeX than there are in LyX so support is not an issue.
Your time is precious, use it wisely.