Mine were delivered today and I managed to get it fitted on the bike before dinner.
Drilling the second pannier got a lot easier than the first. I made a template like the person who wrote the lengthy review, but I found that method was not "100% precise" and caused me a little rework to get all five holes lined up per puck.
Learned from that and just used my template for the center holes then used the big fender washer as my drilling template for the other four holes. Worked like a charm.