I have just started with your program, indeed with dtbooks, and pipeline.
Together they make a pretty good start for epub ebooks using daisy.
However there is a snag, dtbooks version 3 is not accepted by epub it has to be 2005-2.
If this could become an option then Openoffice - odt2daisy - pipeline - to better epub ebooks would be a very nice route
odt2daisy is focus on "Save as DAISY" first.
"Save as Epub" is another big task.
If a DAISY to EPUB transformer for DAISY pipeline is available,
it's possible to include it into odt2daisy.
At the same time, DAISY 4 is close and the compatibility with Epub will be better.