When you export from PowerNurbs, the control mesh and edge/vertex weighting will be lost. However, the object won't change shape, so what you see as the representation of the nurbs surface when you are editing it in PowerNurbs will be maintained in the exported object.

In the SolidWorks version, there are some settings that control how the subd object is displayed. This is basically a preview of the nurbs surface based on the level of subdivisions applied to the control or base mesh. There is also a "Quality" setting for the converted nurbs surface.