The way I understand the reasoning for Edge and Adam switching intruments is Adam was not there when they first recorded the song so Edge had to play the bass part. Since then, they have always played it where they switch instruments. They also assume eachother's position on stage which is cool.
Hello Ruth! I was there on 10/24 in the heart, 3rd row from center stage. In fact, I even have a picture of you on the main stage. I thought you were great and I remember the roar of the crowd when you sung those lyrics. It was a magical night.
Dave