It might be a skill level thing too ACE. Perhaps as the sailors get better the difference is less noticeable? As a generalization I hold pace with the F18's singlehanded going to weather on my Viper, when I was sailing that old A, I was crushing them up wind. Just my experience, and the rest of the world certainly has a deeper talent pool than the U.S.

MkIV might be an old boat, but wasn't there one doing pretty well at worlds this year? I think it had updated boards/blades though.