The I-cat rating will normally differ quite a lot from the Nacra 17 rating, so I don't think Hobie is on the Formula 17 track (unless they will both sell a different formula 17 - I don't even know if there is a real F17 rule box).

Nacra sells the 17 in EU also as F17, except for France where they market it as C104.

Regards,
Gill