A lot of effort has been made to preserve local representation in the system I'm proposing. Even with regional seats, those members would have a strong link to the local community.
I think 338 seats is enough, especially since some MPs don't get a chance as it is to have their private members' bills appear in the order of precedence on the Order Paper. Normally, the order of precedence contains 100 or so bills. If 50 seats, for example, were added, those members would simply sit in the House without having an opportunity to see their bills put to a vote. What would that change?