Projects Data Security - User Access

Hi,

Is there a way of restricting user access to project data (classifications, work and financial plans, expenditures etc...) other than via the Operating Unit / Responsibility route?

I've considered a combination of Cross Project - View profile option (set to 'No' at site level) and responsibility configuration (e.g. removal of 'Expenditure Enquiry - All' menu item), but would still have a problem with full OP data access via reports.

My limited understanding of Role Based Security is that it is pretty much an extension to the Function Security funtionality, so that wouldn't be an option either - correct?

Thanks in advance for any advice/input.