Hello,
Using LibreOffice 4.1.4.2 under Linux Ubuntu. I convert odt to docx by doing:
libreoffice --invisible --convert-to docx:"Office Open XML Text" myfile.odt
The docx output is nice, except that there is a table in the odt input and the boundaries (borders) of this table do not appear in the docx output when it is opened in Word (on a Windows machine).