Can there be independent BU designs for HCM and ERP on the same implementation?

Summary:

We are presently evaluating a Business Unit design in Oracle Fusion where Finance wishes to adopts a 1 LE : 1 BU model to support and control Sub Module activities, while HCM has proposed a regional BU structure (e.g. North, South, NI and Scotland) to enable Position Management and sharing of HCM data across Legal Entities. This in turn would result in the employee assignment BU in HCM completely being independent from the Finance transaction BU. Has anyone implemented a similar model, and were there any practical challenges or limitations observed in areas such as Expenses, Procurement (Requisitions to PO