the 530 will be very stiff for the 9,0 Code:Red. maybe you will be able to planing little bit earlier with the stiffer mast, but you will have serius control problems in mid wind and up - specially in choppy condition.
yes, you have bigger risk to break the mast too, but the main problem is your mast will demage/strech your sail very fast and will loose the performance.
a wrong mast influence the race sails' performance much more than the other sail categories'.
hope its help,