Thank you for your answer!... mainly, the software where I want to export is modo... I have noticed that a complicated mesh from rhino, textured as glass, so transparencies and refraction, was very very time consuming to render, and a sort of "same shape" mesh, directly done in modo, was , with same material, much fastyer to render... So I think that the resulting mesh of the nurbs process is important, and I suppose modo allows ngons... I'll try today ( buy Moi very late yesterday)...
One curiuous thing I noticed, just trying Moi and importing a file from rhino, was the handle of nurbs objects from Tsplines... seems to be imported "before" trhe translation in current nurbs, but I have to test more intensively... Love also the instinctive feeling of Moi, although that the fact to know rhino is probably an help!...
and yes, FP, I'm probably the only one with that firstname in 3d field... there is a french forum already?...