After some investigation why the .obj files I created in Rhino wont load in vvvv, I noticed that it appears that Mesh(DX11.GeometryAssimp) cant seem to handle OBJ files without texture coordinate indices, even though they are optional.
Thanks everyone for your suggestions. I have exported the geometry again from Rhino with texture mapping on. Also had to unweld with an angle of 0 and weld again, to get the polygonal look.
Didnt see the NoTexture method on Gourad, as I only chose that for the example patch here. Actually using Superphysical, which doesnt have the NoTexture method as far as I am aware. But then Superphysical looks better with some textures anyways.