I have used Unigraphics and the Mold Wizard quite extensively over the past years. I was even involved in helping to define requirements for the Mold Wizard product. Unigraphics and Mold Wizard are top notch tools for injection mold design big and small. Unigraphics is unprecidented in its' ability to manipulate imported models from your customers because it is a hybrid modeler (Surfaces, Solids, Wireframe, Parametrics, Explicit Modeling). Unigraphics is the only CAD system able to easily manipulate any data (iges, step, parasolid, acis) with its' direct modeling tools. Unigraphics is the industry leading CAD system in the injection molding industry and should be considered highly.
Best Regards,