All,

I've owned both. I had an Inter 17 with a Spi and I now have an F16.

The F16 is a true formula class.

The F17, Inter 17, Inter 17R are all derivations on the same boat. I believe Nacra decided that it would be smart marketing to call the latest evolution of the Inter 17 the F17; I believe the F17 is the same as the Inter 17R except that the F17 has 2 different size kites depending on how heavy the helm is.