Rhino 7 wip = Rhino 6 sr xx + Rhino 7 new function?

Serengeti (Rhino BETA)
1

Is it right? btw Rhino 7 subd function is well for modeling

2

Hi - that is basically correct, yes. But not strictly limited to new functionality; there are also bug fixes, UI enhancements, etc. that are only in the WIP.
-wim