Bit of revival.
I came across this: https://www.youtube.com/watch?v=bGnrSVQ9ex0
I think he's a Dutch so probably been tried in the south end of the North Sea.
I took a 2 day course for kitesurf in Southeast earlier this week. 20+mph onshore wind but VERY sunny. Wore my winter 5/4/3mm, and aw I was FREEZING! I never noticed how cold it can get when you are wet and out in the wind from wind chill. Major (and obvious) differences from surfing are 1) most of my body would be in or the surface of the water paddling around, 2) I'm constantly moving around paddling, 3) speed would never ever go up to the range of speed kiters would sustain with their kites hence minimal wind-chill factor.
I was expecting to be cold when kiting but not as cold as it actually was. By the time I got out I lost my grip power and dexterity; bit of a mission to untie the lines and pack up... Plus there are quite few fiddly things to do with your hands when kiting like "un/hooking" "sheeting" and "trimming" etc which all involve gripping, pinching, grabbing, etc.
So going back to Ian's suit, I think he's spot on with his IANOVATED wetsuit for wind-watersports. They'd really need that grip power and finger dexterity and feeling cold in your hands doesn't help at all. I'd love to have a go on the suit in the winter time to see how much difference it'll make compared to kiting in an ordinary winter surf wetsuit + gloves.
I thought I'd share my thoughts...