First, the fin was straight and square with the board. I did not detect any undulation, or measure a difference side to side when in position in the box.
I fit the fin without any modification, sanding or otherwise: it was an exact fit, tight but complete.
While sailing I can handle the fin from minimal wind to 25 knots without issues. That is a nice range. What is noticeable is the very low drag, which results in a very fast linear speed on the water. It is a 75-5 and with it I go faster than with a 68 from another brand (slightly older but modern-carbon molded blade as well). I measured speeds in the 26-27mph range regularly with it, and I have not pushed it to the limit yet.
While racing, the only two people that were ahead had boards 4 years newer, which could be a factor, as well as the sailor skillsets of course.
Overall, I enjoy the fin, plainly because it is fun to sail. I have not put any other fin in the board since I got it.
Vincent Barre