Timbo: Stuffing the bows underwater is not such a big deal. The big deal is do they come out? I think that the older design sheds water pretty well. I sail a Tiger and I am always concerned when the water is on the deck. With the deck being so flat it likes to stay underwater longer than the older design of the Nacra F18. I have stuffed it to the crossbar downwind and saved it but that is do mostly to the incredible crew that I have. She sticks to the boat like glue and has never fallen so far forward as to pull the boat over (knock on wood).
The new Nacra is designed to take advantage of the fact that you may sail in swells. If it goes down it will shed water better than even the older F18. As far as it getting there in the first place the bow seems to stay higher out of the water without too much tendency to submarine. The boat steers very easily downwind. It kind of sits up and goes were you point it instantly. I think it may be easy to over control it, steer too much. As a matter of fact, very similar to the way a Hobie Fox steers downwind.
Dan