when you're creating a character with lots of detail you can do it with any form of modeling... in polys you smooth, in subd you add a level of detail, and in nurbs you just add isoparms or hulls. there's no wrong or right, it all depends on preference and ease of use for the modeler. if you want to keep going in nurbs, do it! the poly police aren't gonna break down your door and arrest you.
Accept no substitutions.