There is a point where the added righting moment is larger then what the leeward bow can carry. The wider the platform become vs. length and bouyancy, the easier it will be to pitchpole the platform. The Tornado is 20x10foot, and it is wide enough. I can count on two hands how many times I could have wished for more RM over the last 7 years. But we have raced in uncountable times in weaker winds where we really wished we could have got it up on one hull. It is a severe handicap in the light stuff when narrow boats can fly a hull while the wider boats are locked down with both hulls in the water.
If you live in an area with predominantly strong winds, the extra width and RM makes sense. If you live in an area with medium/weak winds, the extra RM becomes an handicap. Especially as in my opinion the "F20Super" should be designed for sailors a little bit heavier than the current classes. But, why not? Go for it and compare the performance to more narrow boats.. Over time the boats who compete will find the 'sweet spot' for how wide they should be. As long as the rig and sailarea is defined, the RM and optimum width can be calculated.