Hi Michael,
I'm also interested to a function similar to "section plane" of SketchUp.
In Rhino a similar function is "clipping plane" and you can define as many clipping planes as you need defining also thickness and colour of the section border with the possibility to have or not a filled cap (if the volume clipped is a solid). In other SW you can define also clipping volumes.
For complex structures, AEC, and assemblies it is a feature really important.
Thanks,
Giovanni

P.S. In sketchup a minus of "section plane" is that you can have only one section plane active (there are workarounds using groups or components but the workflow is not so easy)