Ok, at the Worlds the guys on Tri-fin boards were:
Sky Solback- who won the first race of the series on a tri-fin Rista board.
Word on the street is that Paolo's board is the fastest, but it takes some getting used to to get the full potential out of it. It seems that this is the board that Rista is showing in the first video. Now Ski never changed a thing and rode the board with the set up Paolo reccommended. If Sky had the time to try some different fin set ups, I am sure he could have gotten more out of the board. I did see Sky out point Damo on an upwind leg, in one super light air race, (Damo weighs 150 and Sky is pushing 200 pounds), so I know the tri has the potential to rock when you get it working.
Gebi- I rode a tri (5 fin Mike's Lab) and used a different fin combo almost every race as I was trying to find the fin balance. As the wind got lighter it seemed I did better, as I started to get my fins figured out. My best race was a 4th, but i took a 17 Zephyr that race and the wind died, so i made a good choice on the kite size.
Alex Aguera- rode his production board with a tri on the first day which was powered 9 and 7 meter conditions and then switched to the quad when it got lighter.
Chip Wasson- Mikes Lab, 5 fin but rode it as a tri the whole regatta. At times Chip was smoking on Starboard tack upwind, but on port could not hold his angle. (Back to finding the fin size and location balance) Chip rode something like 15 to 16 inch front fins and a 10 inch fin in the back.
KC Cambell- Mikes Lab, 5 fin but rode it as a tri the whole regatta. KC had a similar size fins to chip but slightly different location in the fore and aft position.
I received my new board about a week before the event started and since I was waiting for my new fins from Curtis; experimented with custom fins I made and some extras I borrowed from friends, (thanks Kent!) It was super windy and choppier than when we raced the worlds when I was training, so getting downwind with out crashing in the super nasty chop was a bitch on a lit 9 meter.
I was struggling to find the balance with my limited fin quiver (riding my board as a quad) and then I tried the board as a 3 fin. Instantly the board was much easier to ride. I was riding a 13.75 windsurf pointer fin in the back and some 10 inch in the front, and that set up was pretty friendly, especially downwind as you could actually steer the board like a surf board. As a tri the board can be carved rail to rail and as a quad you have to be super careful not to catch a rail while steering the board around.
The tri is much looser making these modern, powerful and stiff riding raceboards much easier to steer. Tacking and jibing is much more relaxed, but the fin set up is much more critical to tuning. Since the tri set up is inherently looser, you have to spend more time to find the balance of fin size, location, angle of cant (angle find are tipped out, usually somewhere from 4 to 10 degrees depending on your taste) , and more importantly the position of the fins in the fore and aft positions. Once you find the balance the board will do things a quad will not do. it takes some serious tuning, but at times you will find the balance in the whole package and learn how to ride these wild horses.
Hope this sheds some light.... without giving up all of the secrets...