The fact that they don't seem to have the claimed speed advantage, and that they may have to race separately, may mean that they won't be the future as some claim.

Well... you either foil... or you don't on the course.... A single number handicap system is doomed to cover this huge performance difference of the design. Then of course... you have to handicap the huge skill factor in flying the boat... can you fly the boat around the entire course... half the course.. or intermittently and so how much of this factor goes into the rating. Its a big ask for a single number rating system.