I'm finding that when I use the 'Create and edit text objects' button, sometimes it's Properties are text, but sometimes 'flowRoot'. The latter looks identical, but when I insert the svg into OO Writer, the text has disappeared (ie. completely gone, not just hidden behind another object).

I'm not sure where the apparent discrepancy is coming from?

If you haven't done yet, you might want to check this thread:
http://www.inkscapeforum.com/viewtopic.php?t=10819

and this:
http://tavmjong.free.fr/INKSCAPE/MANUAL/html/Text-Creating.html#Text-Enter-Flow