Didi confirmed that this should be done for 4.0 4.1 and 4.2 and is critical in order for the migration to succeed.
The updated documentation is available on the Customer Portal: 4.1: https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.1/html-single/data_warehouse_guide/#sect-Migrating_Data_Warehouse_to_a_Separate_Machine 4.0: https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.0/html-single/data_warehouse_guide/#sect-Migrating_Data_Warehouse_to_a_Separate_Machine