I think this will be interesting. DH and I were there this past February and did not have an ADR, we had never eaten there and wanted to try it. We were told it would be a 2 hour wait, they took my cell number and said they would send a text and we would have 15 minutes (I think, it may have been 30) to get back to the podium once we got the text. So we did things in the park for a couple of hours and went back to see where we were on the list, we still had another 30 minute wait before we got our text. We didn't mind the wait since we did not have ADRs, I may have been able to get an ADR last minute, but didn't even look. We were starting dessert when Wishes started and I was able to step outside and watch (DH stayed behind to eat ice cream, which is priority for him over fireworks, lol).
Maybe our wait would have been less no one had an ADR and it was all walk up, but the seating area is so small. I can see this having an hour wait most of the time. The cell phone text/ paging system could work I guess.