In case anyone is interested, my experience with the new system has been mixed. I was able to obtain my PASSID (and my infant son's) via email - I tried calling on Monday but had a wait of over 30 minutes with the number of people in the queue falling from 18 to 12, at which point I gave up!

Yesterday I managed to schedule same day appointments at ORD. On arriving at ORD, interview confirmation letters in hand, I was told that the interview appointment was not valid and that the new system meant that same day appointments, although they could be made on the website, were not reported to the staff. I politely expressed my disappointment and frustration and they let me wait for a walk in slot, which came up shortly afterwards.