The KSO are poor surf shoes if you have to walk across a sandy beach or through a shore break.
They don't seal snugly around your ankle and sand splashes into them. The heel cups around your foot so you can't easily rinse the sand out.
The soles are fairly thick and stiff with articulation points under your toes. I can feel a bit of an edge under my big toe joint where the flex point merges into the harder part under the ball of the foot. It's not uncomfortable, just noticable.
The stability on the foot is pretty good and grip is fine (so far. I have only kited in them on a strapped twint tip)
Because of the sand splashing I would rate them 3-4 out of 10 (being generous) as a surfshoe. I rank my Neil Pryde low ankle booties an 8.
The Flow look like a better model for surfing. Even those ones look a bit dodgey. You really need a little height in the ankle and a draw string bungy to close them snug around your ankle.
Like these
vs