I have another question for this thread: Has anyone had to sign anything upon entry? I can't recall if this has been mentioned already.
With Priority Pass, you used to sign a receipt which was obviously used to remit a certain fee which was collected from PP. I can recall that some Lounges were able to swipe your PP card electronically, while others used the old school click-clack machine... In the US it's even more basic, and you often sign in on a sheet of paper.
Anyway, I ask this question because I'm curious to know whether DJ collects a fee on a per visit basis, or has some sort of other agreement with AMEX in place.