I am just now installed only the Current Content. 

But just to be certain I have not made a sub-optimal decision, could anyone tell me what the Legacy Content might be ?   Is Poser 6 content considered Legacy, so I left that out as well ?  Or have I left out the older Poser 4 (Poser Artist) content ?

Thanks in advance for any helpful comments.

I can only tell what isn't there. Most of the Poser 5 content does NOT exist.
Other legacy content does exist but there is little of it, so I would suggest installing it anyway and getting rid of it manually if you consider it obsolete.

Nude Judy is certainly missing, alright!

If we want to keep those, I assume we can simply transfer them over? Most of my stuff other than legacy is in outside runtimes - the only thing in my Poser 6 runtime is the legacy stuff - which I find nice to keep around.

And of course, the python and other plugins... Once they are all updated (hopefully) I'll just delegate P6 to a testing status for merchant stuff.

P2 high and low res models are still there, as well as the P3 Male and Female nude figures, and P4 figures (high and low).  I'm still rummaging through directories to see what other content is included., so don't yet know what P5 and P6 content was retained.  At 1.7 Gb, there's a lot.