for whats its worth
I've paddled in some large surf in both white water kayaks and sea kayaks and here is my personal experience....
Fors kayaks, great fun if you have the skills, but you can get a serious beating if you get it wrong, so any swell over 2m is very tricky, to get out past the break is the biggest challenge, getting in is fine if you have a good brace and roll, forget about staying upright however. The hybrid surf kayaks are better as they will carve and perform faster.
Slalom kayaks work OK, but are more prone to damage and pearl (nose dive) due to the length and little rocker, but they have speed which helps to get out and catch a wave.
Seakayaks eg 5m long, surfing in large or medium swell is great if you want to practice surviving beach landings in tough conditions, but in general, a large swell like 2m or more you will eventually get punished and have a high chance of injury to your back, neck or shoulders as you can get thrown very violently by a dumping wave. So while its very cool to say you have been out in big surf i your 5,4 seakayak, tt can have a high price (from experience).
Note to any one wanting to try surfing a kayak in surf. You have to stay away from other beach users when kayak surfing, you dont have the same control as a surfer as to what happens when you loose it, a kayak flying along in the surf side ways with you in or worse out of it is like a truck when it hits a swimmer and will make you very unpopular with other surf habitants (board surfers in particular).
And while we dont have real beach breaks with strong currents like rips and under tows here in Sweden, ask locals for advice if you go out from Sweden to another large surf destination, most surfers are happy to give it, after ll its they who often pull in people who get into trouble. Also learn the rules or etiquette when out there.
I just spent a month home in NZ, and many early mornings in 1 to 2m swells on a SUP, when I looked down the coast line I could pick out every 200m another SUP, so you can se it was catching on there in a big way.
If you really want to surf and get the magic feeling, try this, its the best I know and I've tried most things in the surf ;-)
I'll be back there next year (dec-jan), any one keen to join me let me know, I'd be happy to help?
Cheers
James