NSI (nsi.com) or something like that.
They work pretty well. It is a set of stick on pads with inserts. They work good...just expensive.
I am building my own boards so I am putting the inserts inside now. I do have a used set of the NSI pads if you are interested. They still have some of the adhesive, but you should re-glue them (rubber cement will work). Let me know if you want:) It is the Pro set up with heel protectors. I could give you a set of the NSI straps if you want those too for a fraction of the new price.
Depends on the life expectancy you want from the surfboard. "Regular" fiberglass surfboards have thin decks that will not tolerate the pounding of kiting. You will either push your heels through the deck or just break it in half. Ride your surfboard strapless and it will last longer.
Santa Cruz epoxy surfboards by built by Surftech, can handle 50% more abuse and go well with the nice NSI stick on pads and straps. The kite companies have improved the designs of their directionals, plus they build in some extra durability for kiting. The Naish designs are good and durable too, and also look at the new Slingshot Celeritis designed by John Doyle.
Dereck Camacho in West Palm Beach built a 6-0 quad for me that is starting its third season. He gave me the choice of light, regular, or beefy construction and I chose tough. My other favorite is a 6-0 FireWire QuadFlex, which I promise you could not survive with straps.
PS- I ride in surf 100 days a year and I pay for all my equipment. ww