Other possibilities would be something like Dan Caouette's build of the Yahoo and Spray HPK. The latter was a kayak-ified version of a Bjorn T. surfski hull, IIRC.

For spirited flat water paddling I'd build something more Björn's Sea Racer over the Panthera or other surf ski-ified kayaks. Surf ski style hulls are better suited for big off shore water. Björn explained it very well on his Spindrift webpage:

... the rationale goes something like this: the Sea Racer has a flatter run, less rocker resulting in a slightly higher Cp, which in turn means better top speed. The surfski on the other hand has more rocker and lower Cp, meaning lower top speed. But the superior maneuverability, neutral steering and seat in the center of the hull means a softer, drier run and less speed loss in waves. Since the Sea racer is a slightly "surfski-ified" sea kayak the differences may be small – but the surfski has a definitive edge off the wind, where the maneuverability and control will make a huge difference.

The other design is the "Wahoo." It's a low displacement performance design by John Winters. It was optimized for paddlers between 120 and 180 lbs who compete in events that use the Sound Rowers Fast Sea Kayak (FSK) classification. For USCA races with the latest rules, this boat’s 4” waterline width qualifies for “Sea Kayak” class.