Hi Pirrad,
I've had a few fun sessions in the smaller surf with a paddle and an old Wally hull too! I tried to keep away from crowds - at 20+ kg they are a lethal weapon. I think water forcing up the centreboard slot limits them a bit. Great glide across a wave, but at times they just seem to have a mind of their own.
A Kona One paddles OK, but as soon as the wind is 5 knots (or even less) I put a sail up. It's heavier than dedicated SUP boards but for that extra weight you get a board that has genuine planing performance and good light wind wave-sailing. Not sure I would leash one to my leg - could end up with one leg longer than the other :-)
There is discussion of this topic on the Kona forum:
www.kona-windsurfing.com I lust after a Kona 11.5 or 10.5 - OK as SUP, outstanding light wind wave sailing and OK planing performance. Correct me if I'm wrong, but for some dedicated SUP's (Mistral Pacifico?) the balance is: Excellent as SUP, OK light wind wave sailing and no planing performance?
For reference I would rate a Kona One as: Makeshift as an SUP, good light wind wave sailing and good planing performance.
Regards, Richard