Hi, i have a pocketbook 602, i can give you my feedback about tts.
Text to speech is better than good about read and ponctuation, but it rest a mechanical voice for emotion and speed of text. (anyway in french! But it's realy Impressive). It's not easy for run it and in my opinion difficult for a blind man. But if you lunch it, he will can stopped and resume when he want. The pocketbook 602 have Incorporate speaker or you can plug Earphone. You can hear for a longtime, i think about one or two books with one charge of battery, i don't try to listen a full book, I fall sleep before the end ;o) but this object have a longtime battery.
Sorry for my bad english i'm french, i ear regularly my book, i hope You have help in your research.