Finally NVSurround can be used without the fisheye effect. LM has solved it by making special shaders which corrects the distortion.
In P3Dv4.3 :
Open the Menu taskbar in P3D
Go to Views
Go to Manage Camera's
Fill in a name for the new Camera view
At the right from the list at the bottom check "Wideview"
Set the zoom you want ( best 0.31 --> has to be higher than 0.30 )
Save as Scenario
Fly without distortion ...