My experience is that LaTex is too hard/strange for most people (even electrical engineers, so its not about IQ...), and there isn't a better alternative to MS Word for writing big product manuals.
(Also, while having some experience with the system, I do notice that I have a hard time achieving flow while writing LaTex. There are hundreds of WTFs).
I've started doing my academic writing in MultiMarkdown (MMD) using Scrivener. It generates LaTex (or PDFs via LaTex) and for me is even easier than Lyx. When needed, you just embed raw LaTex in the doc as <!--xxx-> comments or just do the final polishing in your usual LaTex editor.
I almost forced the team to choose Markdown, and then had to change my advice and say "Let's go with LaTex" because there are so many features MS Word users want to use... I don't remember exactly the one that prompted the switch - maybe footnotes, tables or referencing.
Have a look at ConTeX (www.contextgarden.net). It is a TeX macro package, just like LaTeX. But it is a MUCH more consistent syntax, heavily relies on LuaTeX, and can generate XML output (for webpage and epub) as well.
Seriously, you will regret not using TexStudio, I guided a friend who installed it on Windows (works on Mac,Linux too) and damnit, it can transform drawings of formulas or anything to LaTeX-Code. That's awesome!
(Also, while having some experience with the system, I do notice that I have a hard time achieving flow while writing LaTex. There are hundreds of WTFs).