During our initial user tests, we noticed that people who want to provide an answer sometime need to ask for additional information to the person who asked the question.
It would be nice if those requests for additional info were done via the WP comments (as each Q&A is a wp_post) rather than by adding an "Answer" into the thread. Likewise, users may want to ask additional clarifications about an Answer.
Because each Question/Answer is a wp_post, this leaves the door open to using wp_comments in each of them. What do you think?