I had the same problem with my Nacra 5.2. I haven't tried the one rudder up trick. I knew that that would reduce drag but I will try it to see if it reduces weather helm too. My main problem is that due to the rope-a-dope rudder system on my Nacra, I am having problems getting the rudders all the way down. Even so, the helm is not unbearable.

-Rob V.
Panama City
Nacra 5.2