I have found this -- it is so far the best voiced TTS I have ever come across:
http://www.loquendo.com/en/demos/demo_tts.htm
I am however a EPUB devotee and for this to work well the book would have to be written in SSML and then included as an extra within the publication container.
Anyone with influence over the manufacturers please pressure them to up the quality of the TTS, it opens-up a whole new world.