We currently have Cases linked to Accounts that are created by:

• Self-Service Portal Users (all of these cases have a Contact)
• Email-to-Case (most are from recognized Contacts who may or may not be SSP user, but many are from folks at our Account who are neither a Contact nor an SSP user)
• Our internal SF users speaking on the phone to customers (all of these cases have a linked Contact and Account)

All of our Self Service Portal Users are super-users.  Any one of them can see all Cases linked to their Account, irrespective of which of the above paths were used to create the case.  This is a critical feature.

We would like to move away from the Self Service Portal and move all our active SSP users to the Customer Portal.  However, they must be able to see all the Cases at their Account.

We know their is no super-user feature in the Customer Portal, but have been told by Salesforce.com that we can effectively create it with Public Groups and Case Sharing Rules.  But can we really?

We can only put Users into Public Groups.   With a Case Sharing Rule that uses the Public Group, we can enable all of the Customer Portal Users to see each others cases.  But, they cannot see the Cases linked to their Account that were created by or for non-portal users. 

Is there a solution for this?