I don't know about that. If you use a well balance boat like a TheMightyHobie18 as an example; Some of them had rudder push right out of the box. Just raking the rudder or rudders back a fraction of a degree would make the boat sail straight. Where as raking the mast aft didn't change much at all. I think tipping the mast one way or another is over rated on it's effect over helm. It doesn't do as much as you might think on a windsurfer either. It is tipping the board with your feet that turns it. At the end of a tack you can rake the mast extremely forward to act like a jib to bring the bow around, and you have to rake the sail back to jump around the front of the mast. You don't steer by raking the mast on a board.

I have the same thing on my little boardless cat as the TheMightyHobie18. I get a neutral helm with the rudders straight down, but just a fraction of a degree too far forward and lee helm kicks in. i don't think there is a crossing of the working center with the pivot center to cause the lee helm/rudder push.

Also i wonder how the Super Cat rudders fit into this story. They have like 3-5 degrees forward rake and the boat sail balanced.

Perhaps Mn3 only has lee helm with the Spi. up. He would either need to live with it or adjust the rudders and hope the rudder tug, if any, doesn't bother him upwind.