Thanks everybody! I now heave a lot of information to ponder and decide on

Some of the graphs here go above my head I am afraid. I want to look at this some more and think about all the arguments.

From a practical point of view I like the simplicity of using the same mould for both rudders and daggerboards.
"Traditional wisdom" or knowlegde says that rudders and foils are very different as the AoA on rudders will be more variable and greater. Thus a different foil is "optimal" for each application. This discussion probably needs some tank testing in a lab to determine the differences?

PS: Last night we built chainplates in carbon for the boat. Will be interesting to see how they come out after cooking.