Many Thanks Christian for your reply.
We are also recommending PO in this case.
As another alternate approach, and considering the license fees for the heavy external user base creation for Business Suite systems, how suitable is LDAP or AD as the authentication mechanism and going with deployment on Gateway HUB itself.
For us, the main decision options here are authentication via PO-UME or on Gateway system (SU01 etc) or User authentication via external authentication servers (like LDAP etc) for the 1000s of external users accessing the app.
Thanks,
Vikrant