A few people had also mentioned in a thread about a month ago that they found with extended listening to TTS the voice eventually faded away and it became similar to just reading in their own head, if that makes any sense. I can't say, I haven't used TTS except for very short demos of the technology during my frequent enabling sessions here at work.

TTS may be like talking to a person with a foreign accent for whom English is not their primary language. I find that the longer I talk with someone like that the easier it is to understand what they are trying to say.