i have a 5.05 gemini waverider and it performs pretty well in some quite startling pacific seas.
Two weeks ago we had her out in the open water when a southerly storm blew in with a vengeance and due to driver error and too much weight at the front of the boat (three people sat in the bow locker and tubes) we went straight under a rather large wave... (about 2.5- 3m).
Unbelievably, we were extremely lucky and whilst we all got completely soaked, the rib came out the other side and got us safely back to harbour.
Take a look at
www.epicsurf.com.au - these guys use a 6m waverider for commercial purposes. It goes out 3 or 4 times a day and gets quite a bit of abuse - see the pictures,
HTH