As I asked earlier; if you keep all the loads the same, same stay tension, same sails, same crew wt. etc. how does the mast know what it's attached to?
I submit that it doesn't.
....
You could argue that if you take an I20 with an A cat rig out in 30knots of wind, the mast will snap, but that's because the (heavier) I20 platform didn't fly a hull to relieve stress, as soon as the A cat would have, and that has allowed you to add more stress to the rig.
You just explained it yourself as well as I could. Added to which, the I20 carries more sail area.
For the same reason you put your rig at risk by putting five large guys on an a-cat while it's blowing 20, an a-cat mast trying to support an I20 sail area and typical crewing weight would be asked to do more than it was designed for...and it would likely break.
