One other thing that you should consider if you are going to try to make the perfect mast, is the shape of the mast. One of the things that is always referred to as extremely important is the leading edge of a foil shape. Any blemishes on the leading edge of a foil will produce drag and easier seperation of flow of air (or water) over the foil. In my opinion, it should be the same with the leading edge of the sail. In his book on high performance sailing, Frank Bethwaite talked about a long squareback wingmast that he pointed straight into the wind as being better than the ovalized shape that we are currently using. I do not know if that is right or not, but it is interesting to consider, but too expensive to try. Other stuff I have read referred to the perfect mast shape to be about 4 times the width, which is about what you get if you take the front percentage of any reasonably efficient wing shape (like the NACA 64020 or 63020) of 10% camber and mirror that shape for the other side of the mast.
On the soft mast issue, if the mast is too soft, it bends in the middle. I have a carbon A-Cat mast that I have to add layers to to get it stiff enough to get power in anything above about 5 knots of wind. Currently,I have to be real careful to not sheet in too hard as this pulls the sail down the mast, bends the mast more, and removes all my power. It is a pretty fine line between having too stiff a mast and too soft a mast. It is probably easier to tailor your own weight to the mast to get it right than it is to change a mast that is not quite right. Far more painful though.
Another thing is with the predominance of the new square top sails on any modern design, the mast top has to be stiffer to get the leetch to stand up when the wind comes up. I was out on my 200 lb A-cat sailing last fall in around 8 to 10 knots of wind beside a Tornado. The T was powered up on a close reach with a person on the trap and the hull up. I was still sitting on the hull because when I would sheet in hard, the sail would pull down, the mast would bend, the top would twist off and there was no power. The mast is actually supposed to be pretty close to optimum for my weight by the bend numbers. In my opinion, I have to stiffen it up a bit. If I stffen it, and then lose 20 lbs, will it be too stiff? Maybe!
If you like all this stuff, you would be real interestin in a Marchaj book titled "Sail Performance". He gets into all kinds of different stuff including the leading edge planform, and other wacky sail shapes that are more efficient than the current bermudan rig. He also tells why it is more efficient, or powerful. By the way, I made my own A-Cat and am considering trying to make a new mast, too. That is a pretty iffy project though.
