Quote - What I think I'm reading here - correct me if I'm wrong - is that VSS is the more polished, task-focused skin-shader tool, where Matmatic is more of a lets-have-a-play-with-making-shaders-by-writing-code sort of tool... I think.

no.  it's what i was explaining before.  the only reason you need Matmatic is if you want to start defining a single material programmatically.  if you want to make a single material manually, it's not helpful.  depending on the number of nodes in your intended material, your experience and comfort with programming, and your comfort in the material room, Matmatic may or may not be helpful to you. 

as i believe i stated previously, VSS has nothing to do with skin.  what VSS does is help you manage material zones. a human is just an example of where you might need this feature.  for example, there's lots of different material zones on most figures that all get similar treatment even if they have different maps.  and you might want a fingernail shader and skin shader to have similarities.  teeth should have a certain treatment, and corneas should have another.  but the same is true of a house.  walls should have a certain treatment, and moldings, and windows, and window frames.  VSS allows you to manage all of those materials.  to apply a transformation to multiple material zones, and taking into account that they all have different maps.  VSS just happens to have default content for working with a human  figure, much the same way Poser as a default comes with a human figure.  if the community and tool were more focused on architecture, VSS would probably come with building shader defaults.