We have been converting Word documents into Arbortext Editor for years now. We have also been searcing for a way to do this automatically. Unfortunately, the only way we have achieved 100% conversion has been through copy/paste. When it comes to tables, we copy the table into Excel first and then copy the table into Arbortext Editor. This is the cleanest way to bring the table contents (columns, headers, etc) into Arbortext Editor.
In my experience, there is nothing out there (yet) that will give you 100% conversion from Word to XML.