It's true that Sigil is very useful for refining the structure of epub
files converted from other file formats. I use Sigil to "clean up" the
many epub files I originally create with Writer. Like others here, I
have experimented with various ways of converting the User Guides to
epub, with much the same results. The issue is that the template used to
create the guides includes many styles and formatting arrangements which
do not readily translate into the limited number of xhtml tags used in
epub documents. While it is definitely possible to work on converted
guides using Sigil, the amount of editing work involved would be more
than that required to recreate the guides in Writer using an epub
"friendly" template of styles. Even then I doubt that the resulting epub
edition would have the same aesthetics and quality of the originals.
If I can find some time (a commodity in short supply) over the next
week, I will try experimenting with some alternative conversion methods
and report back if I find anything that might be worth considering.
Dave