I'm sure that you have heard how poorly the codes went, but I think there was a couple of other areas that caused some stress. Many fans like to plan trips and see multiple shows.
1. The ticket limits were super confusing, and frankly scary. I think all of us get ticket limits, but was it 2 for the member presale + 4 for Citi, and them how many in the regular? Or is that only if you didn't use your Citi card in the presale?
2. Post the ticket prices in advance. The were some fuzzy ranges, but if RedZone are $600 rather than $400 I need to think my strategy through. You don't really know until the first members presale, and that's tough to make plans around. Plus I'm scared if I get RedZone, but they are over my budget and I throw back, what if I don't get anything?
3. Additional shows. I know this is a tricky one. Shows aren't added till the first ones sell out. But some fans may use codes when they would have preferred better seats on an additional day.
I bought Adele fan club tickets last year. They were through the now defunct SongKick. I think the servers were completely overwhelmed, but if you hung in you could get some great tickets. I had to pick them up at will call, but that was fine.
I don't want to complain too much. My codes worked. It just felt like the entire process was more stressful than it needed to be. With that said, I am grateful for the U2 fan club and the moderators. I do appreciate the opportunity to get tickets early, and I loved that they gave out tickets to Trafalgar. Would be even better if they had tickets for the LA listening party!