The round pin is smoother and holds in better and being a quad; it comes off the top "snappier" than a  tri fin board...

Joe has three models different range surf:

Head-High Surf

"5.8P"

Dimensions:
5 foot 8 inch Length
18-1/2 inch width

Available in XTR Epoxy

Quad fin placement and remaining dimensions are confidential

8-10 Feet Overhead

"5.9P"

Dimensions:
5 foot 9 inch Length
17-1/2 inch width

Available in XTR Epoxy

Quad fin placement and remaining dimensions are confidential