After spending the last 10 months in WDW and this past weekend in DLR, I definitely missed MagicBands. Part of it is that WDW is built for larger crowds and understands how to be expedient, but the process of park entrance/FP redemption with the paper passes seemed so tedious. I have never had to wait in as long a line to enter Magic Kingdom as I did to enter DL, I'm positive a major part of that is the process of paper passes. Some of the lines to get fastpasses were also longer than I have ever seen any kiosk out here. Radiator Springs (outlier, I know) had at least a 30 minute line for a good portion of the morning until they ran out.
I don't think that MDX as it is in WDW would work in DLR, but a version of it wouldn't be terrible IMO