@brokenstaral said:
...in fact i find the section-cut ruby isn't as much useful as i had expected...
It is (or can be) indeed very useful. True it is mainly useful for a SU output but keep in mind that section cuts cannot be exported into any rendering apps.
SectionCutFace actually creates a group which (or the different faces of which) you can paint just like any other face OR use it as a "saw" to intersect your geometry and still keep a face after you deleted unwanted geometry. Now this cut cafe can already be exported (otherwise you would end up with hollow geometry and a bunch of back faces that export awfully into other apps).