I think there should be a global slicer object with an include/exclude list. Applying a slice modifier to a large number of objects is extremely sluggish in the viewport. Id much rather have a single object that is essentially a helper that can slice geometry both in the viewport and at rendertime depending on checkbox selection.
Grouping objects and applying a slice to the group is still very very slow when the group might contain 1000 objects for things like a building floorplan cutaway.
