It looks like the new Naish Stealths are complete different from last couple of years. At first sight I see a tighter leech. Looks like a Gaastra Vapor design!
I don’t know the rider on the pictures, if you reconize the rider maybe we could get some real valuable information. Off course it is new sail, I hope for this surfer that the sail isn’t rigged very well. Check his harnasslines and handposition, but also his bodyweight is completly forwarded.
He is obvisious sailing upwind. Till this point I would describe the sail as a sail with lots of vertical lift, a stressed leech design. If this is all true, it would mean comming from the old stealth (2006/2007/2008) you have to use 0.5-1.5m2 smaller sail in the same conditions…