If the crew is hiking hard, actively trimming the main sheet, and flying a hull as they are supposed to, these speeds are achievable. For long distance events, fatigue will set in and the speeds go down. The F18 requires a very active main sheet and they are very loaded up compared to other...
Overall, the French designs have always been good performers downwind especially in breeze. My Phantom was the same way, lots of volume where you needed it. Here's a pic of Matthieu and I in SF a few years back. Matt flew around headstay at the bear away but we still were able to save it and...