Recently there has been a lot of debate on which of these fin setups work better. This issue has made a recent resurgence with many of the top pros including Kelly Slater, Dane Reynolds, and Bruce Irons wielding the four fin option. While the quad fin surfboards are increasingly popular, both Twin and Quad have their own unique characteristics. Because of the lack of center fin, both options ride faster than their more contemporary thruster counterpart. Both are also much looser while turning than a thruster because of the elimination of the center anchor point.
Twin Fin Surfboards:
While both are looser while turning, you really feel a significant difference on the twin. Think of it this way, when the fins are small and there are less of them, so therefore the hold is not as great. The fewer anchor points in the water, the less resistance you are going to feel and therefore rail to rail surfing is a must. Because the fins are usually placed closer to the tail of the board the pivot point also has been moved back on the twin fins.
Quad Fin Surfboards:
While this setup was first brought to the surfing stage in the early 1980's, when the thruster was fresh on the scene.It offered an alternative to the thruster, and provided a ride similar to the twin but with better holding power.The quads also provide much more drive then the twins.This is because the two fins on each side work together to channel the water out the tail of the board. Because the fins are set farther forward on the quads, the pivot point is pushed off the tail more than a twin. Another positive attribute is the ability to hold better in larger surf.This is why you will see many of the big wave chargers using quads.
Difference types of surfers prefer different types of surfboards. Each fin setup has their own pluses and minuses which can only be evaluated and chosen by the surfer themselves.