So after another round of emails and some more research, I learned the following:

• "Priority security" just means the Premier Access lane
• "Priority boarding" just means Group 2. (Group 2! My family already gets Group 1 through our *G status and J tickets.)

I was hoping that this service would be like AA Five Star, which does provide an elevated level of service beyond what mid tier elites get. But that is not the case.
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