regarding to the sunderland: definately donīt think it would be dead meat in the arena. i know of a incident where one sunderland got involved in a battle with six (!) ju88 near the coast of norway. outcome was, the sunderland downed one ju88, damaged another one, and made the four others flee - iīll post a referer asap (i know this story is haunting my book shelf somewhere).
anyways, i still think the addition of flying boats wouldnīt be that big. theyīre slow, huuuge (i.e. easy to spot, easy to hit) and also they need a scenery where they would face extensive sub and ground traffic, i.e. as long as there are no subs and only cv or pt groups, i donīt see a point in flying those winged barns. prove me wrong plz :))