One question I have is when developing the package on your local machine and then running tests in each environment do you set package security up to a specific account?
The way I handle this is by using the SQL Agent account or proxy. The package doesn't have any different security persay, but the security of the different agent/proxy accounts varries. Infact I developed a way to have one SSIS_configurations table for several environments.
SSIS_configurations can be a view/function that returns the data depending on what account (suser_sname()) calls it.