In regards to the rounded pins.....
When I was living and surfing the gold coast I was using a little deeper single double concave with a rounded square tail- this was great for generating speed fast and the rounded square had more surface area that made it easier to change direction rapidly - eg. snap , cuttie but would slide a little on a sucky face. Great fun for punchy Dbah or T.O.S.
Once I moved West that style of board wouldnt work as well. I started to ride rounded pins with less concave . The rounded pin helped me hold the line in the barrel and wouldnt slide around- it sorta just sticks there yet still fast and easy to generate speed (only on sucky face).
The rails are longer and I noticed that I could draw my cutback out longer and hold my speed through the whole turn rather on a square I would slide out a little and loose speed.
Rounded pins dont work well in fat surf- they bog rail easy because not enough surface area where as square would hold speed , kinda like a fish.
Ask K.S. - Most of his boards are rounded pins.
ANyway - I found this. It explains things a bit more.
