Quote -
Because : Once you SubD, you can NOT go back.
Too many figures have been "lost" because the builders SubD too early and could not correct the base any more.

 

That's not entirely accurate. I don't know what apps are being used here but if you haven't done any additional polygonal changes after subdividing (ie. adding or removing polygons manually or changing edge flow), ZBrush is more than capable of reverting your mesh back to its starting point.  That assumes the OP has ZBrush. 

Hello Teyon.
You are right.
But. :-)

You knew the "but" was coming right? :-)

For the "home end user", I fear Zbrush is a bit steep on $$$.

I do the average retopology on small area's in Hex and Blender but to reduce a full SubD figure back to basics??
Hello, good morning, good evening and good 'the rest of the week" - read month. :-)
Na, my "spare" hobby time is worth more.

It is not that hard to reduce a character to a much slimmer obj, but it is time consuming...

The Bsurface and Loop tools in Blender are very handy for this.

Silo lets you go back and forth between subD levels unless you choose to start modying the subD mesh.. then you are baked in at whatever your current subD level is. 

I usually go through my subD'd models and delete edgeloops that dont seem to serve much purpose.  It can take a while but it gives me a chance to review my whole mesh

Quote - It is not that hard to reduce a character to a much slimmer obj, but it is time consuming...

The Bsurface and Loop tools in Blender are very handy for this.

Quote - Hello Teyon.
You are right.
But. :-)

You knew the "but" was coming right? :-)

For the "home end user", I fear Zbrush is a bit steep on $$$.

I do the average retopology on small area's in Hex and Blender but to reduce a full SubD figure back to basics??
Hello, good morning, good evening and good 'the rest of the week" - read month. :-)
Na, my "spare" hobby time is worth more.

V4 was modeled to about 4000 polycount then SubD twice and froze.
once froze ya can't go back.at least not in LW,C4D.

V5 I'm not sure how she was modled.
but not with zBrush remesh but with MudBox and maybe some others or Modo.
They could have remeshed her.