I think that the point about custom characters is a good one. For some people the voices offered and entonation, work. For other doesn't. So I think that it would be nice, as an option, to turn off the main character voice.
And I think that people would also appreciate the option to select among 3-4 "personalities", one of them "stoic" that afect the type of expressions. But since I don't know if it is feasible, an option to be inexpressive might be ok too.
