For starters, they don't make the HPX-T anymore. Not sure what the last model year was, but they quit producing them about two years ago - my guess. The S has a softer ride because it has a bit more V where the T has some in the front and it's flat at the transom (no deadrise). The T has a significant tunnel and the S just has a pocket. Poling depth is probably within an inch either way, and maybe the S has a slight advantage. They can both run super-skinny with an edge to the T because of the tunnel. The T makes the biggest difference on the shallow water hole shot. Both are great boats, it just depends on what is more important to you. I've owned a T since 2002, and have only ridden on an S.