What is your experience
What is your recommendation (brand, model?)
I wear an older model of a windsurfing helmet which looks like an icehockey helmet. I find it quite comfortable, it has several open spots, e.g. at the ears, so that hearing is not impaired.
You make a number of good points for helmet use below Wolfgang. Too many people plan for only a fixed set of possible occurrances while kiteboarding and setup accordingly. Most of the time they will be right and just fine.
A portion of the time, for some among our number, circumstances will fall like a ton of bricks that aren't in this preconceived picture of events and an accident will occur. If they took the care to add a bit of safety gear, a knife to cut that line you are being dragged or cut by, an impact vest to protect your ribs from that nasty impact or a helmet to try reduce injury from that unplaned dragging and impact, etc..
Accidents can and will happen whether we choose to recognize this or ignore the possibility and take suitable precautions. Accidents are happening with regularity as most of us will notice.
My advice is to obtain the best fitting, padded, light and functional helmet for kiteboarding that you can find. Price should be secondary as you are trying to protect the most valuable resource that you have. Many riders use and like the Ace Wake. It seems to be fairly well padded, light, well secured and it isn't that expensive at about $60. USD. There are other models out there that may be worth looking into as well but they should be light, well fitting, well padded, comfortable, have low drag, a good shell, not retain water weight, etc..
If you are looking for optimal performance in a kite, do you buy the least costly one that you can find ignoring all other factors? Your brain and its continuing function are far more important than that. How many people have been saved by seat belts vs. the number that routinely wear them while driving?
More ideas about helmets, selection and related matters appear at:
It is all about choices, no one is forcing anyone to do or wear anything. Do your research and choose well.