Just used it a few minutes ago but was actually channeled to the end entry as there were already 5 people ahead of me in the Priority Lane but nobody in any of the others! I had both an ExecClass boarding pass, my SE status, and my Amex card...to use to get into the Amex lounge where I am now and finally found!
I have experienced the same thing on evening international departures where the Pirotiy Line is the only one open, other than a dedicated one for Air India!
If Amex is paying GTAA for this priority service, they had best ask for their money back.