I like how shell handles the holes. its parametric, adjustable and straight forward solution. You can change shape of hole any time, move it and edit it
Morphs have their own sub,union, inters command and they are final. When you execute subt on morphs, its final. You can't change it anymore, its not parametric but visually its finished.
So looking at this up i would create something like that but mixed and parametric.
When you define shape of operator element and you execute subtraction command i would add little boolean with option that i want this subtraction to be final like in morph visually( movable with object, copy too) and parametric like hole in shell (i can still edit it later in wireframe in 3D or in plan shape of operator no matter what element it is)
Archicad is sooo powerfull and i didn't understand it as long as i didn't learned GDL. NOw i see world around me trough block, prisms,GDL commands, for i=0 to n loops...Its funny
Graphisoft somehow should unlock these powers and make it more available trough parametric modeling. Its there, its part of archicad since its beginigs.
Imagine that you draw something then mathematically explain what that object will do, in 3D window looking at live transformations, rotations,sub,unions, intersections....
intelligently represented at plans, sections + archicad documentation, calculations, thermal calculations....
wicked
But your idea about copying will do the job too !