Hi Wouter,
I saw a T4.9 at the Tradewinds Regatta two weeks ago for the first time. That boat looks like a great design. Did you design that one? It reminds me of Poison Ivy.
Good boat design has weather helm for two reasons: 1) From a boat performance point of view you always want weather helm. The daggerboard is always generating lift to windward. When the rudder is lifting in the same direction, the induced drag from the two foils is a minimun. If the rudder is producing lee helm, opposite the daggerboard, then the daggerboard must generate lift equal and opposite the sail side force plus generate additional side force to windward to overcome the negative side force the rudder is generating, lee helm. This situation, lee helm, makes the daggerboard work harder, generate more lift, which makes more drag. 2)Helm satbility. You want the helm to always to be pulling lightly in the same direction from the skipper for ease of handling. You do not want the helm to reverse between weather and lee helm, especially unexpectedly. This makes the boat difficult to sail well and it is draggy underwater; a slower boat results.
I'm not going to address the rest of your comments because I see an ugly attitude and your goal here is not to help anyone.
So long,
Bill