Another reason to have two units (stereo). . .
A couple of weeks ago I loaded up the two Nano 300s and went to a job at the supper club. As I was setting up I realized I had left the two high-end speakers for one of the units at home. I just forgot to place them in their holder underneath the base (bass) unit.
No problem, I just set the remaining one up in stereo and never missed a beat.
I always have a backup for everything with me but rarely have occasion to use one except if something fails, or my old-age memory failed, as it did this time.