Mast stiffness and sail shape question
What are the consequences of using a stiffer vs softer mast in a sail? Equivalently using longer extension to substitute for longer mast. Many sailmakers give option of say using 460 mast or 490 mast with longer extension in a given sail size.
Does the stiffer mast make the draft shallower or deeper when rigged correctly? What is the tradeoff as far as improved low end or top end when going with stiffer/softer masts?
I've heard of heavyweights using stiffer masts. Is that to create a deeper draft to get the heavier sailor going, or is it to reduce the rigs deflection as the heavyweights greater mass moves in gusts or through chop.
I guess the first part of my question refers to how a sail responds to mast stiffness in a static sense - how does the sail look when rigged. Would you apply less downhaul when using the stiffer mast?
And the second part refers to the dynamic aspect - does the sail feel soft or stiff when pumping or when sailing through chop.
I'm most interested in the effect on race and salom sails. It's interesting how North tells you to downhaul until there's a crease at a marked point on the sail. Maui sails tells you to downhaul to a specified measurement relative to the extension. So, if you substitute a stiffer mast into a North sail, would you still downhaul to the same point on the sail?
Thanks for any insights!