Since there seems to be some interest in this, I would like to offer my alternative experience.
I am a great believer in outlines for anything longer than a letter to Mum. I also use them the way that Steve talks about - outline - write - outline, etc. My first experience was with Thinktank back in the prehistoric era. It had a neat feature called "Hoist": one part of the outline was made to appear as the whole - a chapter in a book could be "hoisted" for that day's work and the rest of the material was well and truly out of the way. It is a form of "folding". This "hoisting" is **very** valuable when writing longer texts. Emacs can be made to behave the same way with outline-minor-mode and foldout. The "hoist" is actually the foldout-zoom-subtree command. You can use outlining and write directly in LaTeX. So, what I do is much as described by Steve except at the end I can import a LaTeX file into LyX. Of course, it depends on whether you like emacs. I understand that not all people do :-). It would be a valuable feature to add directly to LyX (in case the developers have a lot of extra time on their hands!!!). Cheers, Alan