FWIW here's my end-user experience with the shirts:
When I registered I asked the friendly booth folks where the shirt were, and they told me they'd be available on the expo floor.
When the expo opened I saw a line, but I noticed it was moving along well enough so I queued up.
Had some pleasant conversation with others in queue, but brief since it took less than two minutes to get to the front.
Once it was my turn, badge was scanned and shirt in hand in just a few seconds, including the extra time required to answer a question I had about sizes.
Total elapsed time for me: ~150 seconds.
TL;DR: I'm okay with the process used at SCaLE 15x.