SRM - Classic or Extended Classic - both?

We are in the process of building a SRM sandbox environment, and the business team are stating that they are expecting to leverage a 'hybrid' approach to implementing the system where they have some functionality from the Classic scenario and some from the Extended Classic. Is this feasible?

We are already live on ECC6EHP8, and we have a PO 7.5 box. For this sandbox environment, we have stood up a single SRM 7.14 server with the db, an AS ABAP and AS Java stack. We created a second client for SUS but have not done any config yet.

From the master guide it appears there are three technical scenarios: Standalone, Classic and Extended classic. Presuming that a hybrid scenario approach is feasible, should I implement the Extended Classic implementation steps?