I'd like to see if I understand the principle of the thing... Is the issue that with a soft sail, as the speed of the air over the sail increases, part of the available energy gets lost deforming the sail surface, but that a solid wing doesn't deform as much and so more energy gets translated into lift?

Personally I think this is a really interesting project (perfect for A Class, as others have pointed out) and one we should all keep an eye on, but considering the general philosophy of formula sailing ("mildly restricted class rules indicative of a controlled development class... small advancements in handling and general behaviour of the designs are allowed") I don't anticipate a move away from soft sails for existing formula classes in the near term.