Need guidance on Inheriting attributeValues from Parent to Child Item as Configuration/Customization

As part of Oracle SAAS under PIM, we would like to understand the basis of categorization between Configuration and Customization.

Scenario: Inheriting the attribute values from Parent Item to child item.

Approach: Invoking global functions through item rules whenever attribute changes in the parent item, the same values should be updated at child item level.

Questions for the above scenario:

1. When we go with this approach will fall under configuration or customization.

2. These impacts whenever oracle quarterly upgrades happen?

3. Does this will be performance bottleneck?

As per the Oracle documents, it is not very clear for few cases if the solution falls under Configuration or Customization.