The Firefly's smooth polygons doesn't support weight mapping - it's global to the whole object. SSD modelers allow you to map (by vertex or edge) different smoothing amounts across the cage. This smoothing is parametric in nature (like displacement mapping in P5) which makes for dramatically smaller files. Areas that are mapped to be "flat" in SSD come in rounded with Poser's Smooth Polygons which looks quite different. Freezing the object forces the system to create the actual fixed mesh.