nurbs over ploys is just preference

if u use polys ul have a face on top/bottom with too many side an my effect render

if u use nurbs u dont need to attahc the suraces
if u need a roun edge use the round edge tool
just group the sufaces an animate
in attribrute editor for each surface tutn tessilation of U AND V up to highest quality and a value of 5-10 an they will render fine