When a developer runs the package from their machine, it will (in our case) connect as dbo to the Configuration View - the reason being the SSIS developers our part of a group that has higher privs on DEV. If you use sql logins, there will be a bit more management involved when doing the promotes from the developer, to the qa system, etc. When we move the package to a Test environment, the credential/proxy take care of the security. The package execution takes on its (job step owners) credentials.

If I missed the question, please re-phrase and I will give it another shot.