great & thanks Tig And it is great that the interpolated colors from the now deleted textures remain

Ah yes, the repeating pattern problem.. I know what you mean. Been there.. Well it's possible to reposition textures, rotate and resize them to create variations. Also 2dBoolean will pickup multiple textures/materials and you could apply same amount off pushpull to them all. But then again, you might want more flexibility then what premade component-patterns can offer so your current workflow might be more convenient.

Check this fresh plugin: Physically-Based Rendering

Yes. Just control them with layer visibility in each scene. Should work.