I agree - no info.
This sail is a bit special, and in light of the lack of info, there is a lot of info to share indeed. (And copy-pasting the brochure doesn't add to the conversation.)
Here's my unsollicited experience. For a number of outings, I used this sail in lighter winds, mostly on a SB SUP 12', for teach, trying it myself, etc. It is the 6.5m version.
But couldn't get it to work. Problem was 2-fold (no pun), Firstly it would show real ugly creases, like huge lines, from certain parts of the sleeve to the clew. Second and more important, an ugly part of the fat head would collapse, like really, onto the sail under tension or strong wind. That was really disgraceful. Thought I had a dod.
Tried different masts, and different people to rig it, just it case it was me.
FINALLY, I had it to work, and real well too, this very weekend. Trick was: quite loose bottom and clew. About simple as that - mast was a 460, a 25 I believe. I've never tried this before, sounded impossible, but it worked about perfectly.
First, in lighter winds - I was teaching someone. Was a bit baggy, but nice, as if baggy by design. Teaching went well due to light winds.
Then the wind picked up to 16 knots and I tried the rig. I just couldn't believe it. The top part didn't fold, and was handling quite OK on a reach, and super on a broad-reach. I was planing a 12' 6" with that sail !!!
Now of course this is not a performance sail, it's meant to be light and rig up quickly. And that it does.
So my apologies to Mr. Severne for a couple of swear words over the last year...
BTW: no, this is not the same 'Dacron' as the old Windsurfers, and it doesn't rig like one at all - no analogy there. The old Windsurfers were tight sails - you had to pull real hard for them to perform. The bagginess not the same at all from the tri sails nor the old fat heads.