Title says it all. Anyone got experience with both? I need to get a helmet.
Been looking at these - dmcfins.com/collections/accessories
I have used both, plus bump cap. I've used a Gath for a long time, but found I was getting whiplash from high speed wipeouts, and thought maybe bucket effect of larger surface area helmet was contributing. We mostly surf with hoods, so have been using a bump cap under hood, gives a little protection, not as much as a helmet but would help I think. Have put it in a ball cap / surf hat too in summer.
Lately I have been using a Decathlon soft surf helmet, along lines of your link. Seems a happy medium, though isn't helping my coolness factor.
I have both - a DMC soft helmet and a hard helmet - for wind foiling and wing foiling. I managed to bang my forehead on the board last week while wearing the soft helmet on one of my many wing foil dismounts (my winging is very much work in progress). I don't think the soft helmet did much to soften the impact - it still hurt. So I'm sticking with the hard helmet at least until winging skills improve, and even then - if I'm worried enough about banging my head to wear a helmet then I think it'll be the hard helmet. The soft helmet offers some good sun protection (with neck cover) but in my opinion only a modicum of impact protection. Maybe the protection from cuts is worthwhile...
I wear a bump cap in a trucker cap.
If any any of you doubt the benefit of even a little padding, take the handle of a screwdriver and tap yourself on the head with and without your headgear. 
It all works and even if you just prevent stitches it's a win imho.
I started a thread on helmets the other week as I fractured my skull in multiple spots after collecting the foil in whitewater in the wave. I had a look at the dmc soft helmet and it really didn't offer any more protection than a hood. And coming into summer I think it would get really hot. I just had my first session back today after my injury and got a wip weflex from kite republic after trying on heaps of different helmets and it performed really well! It is super lightweight and I hardly noticed I was wearing anything and I'm not a hat or helmet person! I'm yet to try it prone surfing so I'm not sure how it will perform when you add duck diving but on the wing I think it's great!
Got sick of whiplashes when doing speed runs using a helmet so switched to this soft one decathlon.com.au/products/helmet-for-surfing so much nicer just hotter under the sun
I never wear a helmet kite foiling because of the whiplash injuries. Impacts with the gear are very rare because the kite pulls you clear. The boards and foils are very small and light and I ride with straps.
I always wear a helmet wing foiling. Bumps are frequent because of the board and foil being so bulky and attached with a leash. I haven't found whiplash to be a problem with the wing. The speed is relatively slow and there's no real power like you get from a kite. The dynamics of kite and wing crashes are very different.
For winging I wear a Gath convertible surf hat. It's light enough and has good protection low on the back of the head. The adjustment system is garbage. It's a set of self-adhesive strips intended to pad the helmet to fit. They come off within a couple of days. I threw the strips away and pad the helmet with a peaked cap under it in summer, and a wetsuit hood in winter. That makes for a very comfortable fit.
I looked into soft helmets. Most of them had a lace-up adjustment down the back. I don't like the idea of a gap in the protection right up the back of my head. More than once the board has come up and tapped on the back of my helmet to say hello.
I guess I'm going to go with the hard helmet. I haven't really felt the need for a helmet when winging on flat water, but in waves and whitewater, I've been feeling a little exposed.
I had an incident when I first tried prone foil surfing where I really got my bell run after a jackknife fall, and I don't want a repeat.
