I got no response from the message drop on the KA website.
It's marketed as a freestyle sail.
I was particularly interested in the 5.2
I'm curious about the stability/range as it's a 4 batten sail. The only other 4 batten sail I have used is a 5.7 Ezzy Elite and that's stable enough.
Also curious about weight and durability, and its fit on a drop shape 400.
I would be using it for bump and jump and freestyle with lots of crashes.
NotWal, yes we have some reviews from the crew in Europe and Curacao who have been using both the proto's and production sails. I am camping this week with only my phone but will get Peter to fish out some feedback we have received.
Hey NotWal,
I have a 5.2 KA Sail Kaos since about 1 year now and still love it.
Its a high quality sail for flatwater. Especially the short boom is awesome for freestyle moves. Find some pics of the sail at www.masthoch.de/material/segel/
I never tried it with a dropshap mast. Should be better on a rdm.
What moves are you working on?
All the best
Claudius
Hi,
I have the 4.8 Kaos and it's amazing. Super light in the hands and has a big range (i use it from 15 knots till 30 knots).
I already have my sail a year and used it many times and still in good condition!
The sail is also very nice for ducking, the sail is super stable and powerfull.
If you need more information about the sails, let me know ;)
Hey NotWal !
I reviewed the 5.2 Kaos few weeks ago ! You can find some pictures of the details and the video with the whole review (with available english subtitles thank's to the "CC" button) here : tests-windsurf.blogspot.com/2016/03/test.html
In my opinion this sail is awesome for lightwind flatwater freestyle as it's very lightweight, lighthandling, stable and playfull ! 
But the range is great too : I used it in 15knts with 25knts gusts (I'm in Leucate, South of France, with mainly gusty wind) without any problem. You have all the details in the video. I've been pleased as I didn't expect it from a 4 batten sail (I usually use tje KA Killer, the 5 batten wave sail in the range).
For the dropshap mast I don't know neither, but like masthoch I think a RDM would be better. For the lenght, 400 are what you need ! 
For the durability, contrary to masthoch and Milan, my sail is quite new so I don't have the perspective. The sail is well built (reinforcements, double seams, tri-axial X-ply on weak points...) but has thinner monofilm (it's why the sail feels so nicely light in the hands), so I wouldn't bring it into big waves. But for freestyle, bump and jump, and even small waves : no problem in my opinion ! 
"Old dude trying to catch up on old school freestyle..." => I like this !
Fot the drop shape what is sure is you need a small top section, what is actually the definition of drop shape... For the bottom section I don't know, perhaps mr love has more idea about it.
And I can understand your hesitation with thin monofilm has I had the same. But Claudius seems to have no problem, okay he lives in Germany so not a good example as he doesn't see sun that often ! 
Hopefully, Milan has no problem neither and he lives in Curaçao where the sun shines for real !
Can't comment on the North Drop shape, we have not tested the sail on that mast and I won't speculate. The ideal bend curve is 13.5% and the best mast is obviously an KA RDM .
The monofilm is 5mil so not any thinner than normal.
