Thom,
This is an issue for the boats designer. Remember that the series is a formula series and boats that fall with in the formula are eligible to race (upon review of the PRO and committee). The original question is "Should the sc22 be allowed to compete". Also, remember that there are a couple of new boats in the design phase to compete in the formula series.
Personally, most boats are over engineered to a point that 425lbs on the wire is still 425lbs on the wire whether it is split two or three ways. There are some dynamic differences but they are minor.
One of the designs that I have seen is similar to the Marstrom 20 in layout and looks like it would be an interesting boat to sail.
Thanks
Steve