IMO the perceived improvement in bending comes from the sub-d function, not weight painting.  Sub-d not only subdivides the mesh it also smooths out the vertices.  A lot of the creasing and bunching up of the mesh that happens without sub-d is smoothed over.  I used the V3RR and M3RR figures for a long time with Studio and with sub-d applied they looked just as good if not better than the high-poly versions.  Of course the bending doesn't look any more realistic it just looks less strange or noticably weird.