I keep meaning to mention that there is another plug-in for OpenOffice and LibreOffice called Writer2EPub - and you can talk about it
right here on MR. I've never used it, so I can't speak for its results, but a quick glance at the website shows that it does offer optional breaking by heading levels 1, 2 and 3, and is supposed to be compatible with LO v4.
It looks to me like writer2xhtml offers more control, but that's only useful if you can get it to work.

I will drop a note here if I hear anything from the developer of writer2xhtml.