Well it has taken a fair bit of mucking around and many emails back and forth with Cris Ellis who is an absolute wealth of knowledge, up there with the best customer service I've ever dealt with
Almost got my curvature map as good as I am going to get it, maybe some slight fine turning here and there but I don't think there is a lot more I can do at the present stage.
P.S.
Don't mind the strange stacking in some of the corners of the mosaic, using the wrong reference frame