The SP's increased rocker, greater bow volume, harder chines, and flatter mid-hull cross-section, all contribute to its performance in the rough. It's extremely nimble, surfs exceedingly well, and avoids pearling. Produced in a stronger Lay-up, the SP provides everything you’d expect from a true ocean going play-boat.
I had a Valley Gemini SP RM and found it to be an excellent all-round sea kayak with the main point of difference being its short length and therefore, a lighter carry. It performs excellently in rough water, is highly manoeuvrable and decent in surf, as well as being genuinely able to keep pace with the longer kayaks. In rougher conditions, or paddling into a strong wind, the Gemini can be at the head of the pack if you make use of its ability to pick up free runs on wind waves. It tracks superbly, is easy to turn & easy to roll. I honestly can't think of a better kayak to plonk a beginner into and watch them grow. In my experience it had no obvious vices and while some perhaps promote it as a surf kayak, it isn't that. But it does cope well in surf. Just be sure you have a tight fitting, strong neoprene spraydeck as I've had the lightweight Reed thingy implode on me twice and the kayak fill up with water, which I then had to paddle out the back to safety & empty. Its the case with a lot of roto-moulded kayaks and not a fault of the Gemini specifically. I highly recommend this kayak and suggest that it might be all you ever need as it will cover many bases and is a fun & responsive -feeling boat to paddle just about anywhere.