how about
allowing more than 20 last discussions posted to in the listing?
also with the Q&A.
with the Q&A allow user to removed closed questions from current list, or else break list of questions answered into open and closed.
the more active someone is, the less use the current limits are in tracking questions and discussions participating in.
maybe adjust listing to bring to top any discussions with new posts, so ones that have run thier course drop off the list of active quicker.