Gotta say that zBrush and Modo are right now some of the most accessible and powerful SubD modelers out right now add in GoZ and the two softwares talk to each other so designs update. zBrush definitely has some vooodooo magic under the under hood that requires keeping track of high polygon geometries that need to brought down to something reasonable for conversion to CAD (Pro/e, SW, IV…etc). Also, and this is pretty unique in industry, Modo’s plug in Power SubD allows for pre-processing of the geometry so that edges can be set up when converting to NURBS. Normally a mesh, be it composed of tri’s or quads, can get a quilted NURBS patch that is very “disorganized” which really creates challenges for say creating parting lines for molds or adding draft.