The A cats are currently voting on the "hydrofoil" rule- if you look at the"explanation" with the accompanying vote it is stated that at present, with the new rule, allowing canted or curved boards, it is not possible to develop an A cat that will "fly" all the way around the course and this is what the class is trying to prevent.
As for the canting mast- if you are asking about "A"'s- What about "C" class cats? I am sure it's been tried in the "A"'s- they have tried everything else- but currently, as pointed out in the A explanation, all the major championships have been won on fairly standard platforms and rigs.
One thing one must always remember is there is always a price to pay for any "benefit"- ie a particular setup that may be blazingly fast in 10-15 may be unsailable over that and slower in lighter air- this is apparently proving to be the case with the A's. Canting rigs may be quicker in a long straight line, but less reliable, heavier, slower to tack, etc. Look at Ben Hall's "winged" A-cat- much faster in certain conditions on certain points of sail but not faster over all and much more expensive/harder to rig/etc.

Kirt