What I found interesting was the flexibility in the way you could listen to the concert. Audience members came and went as they pleased. They either sat down to focus on the music, or some just lingered or merely walked on past.
This recognises that different audience members will have different attention spans for a multitude of reasons. Conditioned by classical concerts, it made me feel quite awkward to leave half way through the set, as it seemed disrespectful to the musicians. However, I came away with a much more positive memory of the experience having left when I had reached saturation point, rather than forcing myself to listen to it all and get bored.
Perhaps we should try to offer this flexibility in classical concert too? However, this would not be as feasible in a paid concert, as audience members may feel that they had to get their monies worth. Perhaps we could offer an alternative activity if people needed a break from the music i.e. go and get a drink (like during the Night Shift concerts by OAE) or provide paper and pencils for drawing activities.