I usually don't bring one, I've brought one a few times and I've never needed it...BUT - there is always that chance isn't there?
Our guitarist has broken strings and had to change a few times, the only thing about a backup is its something else to possibly get nicked when at a gig. I may get a cheap squier bronco or something to stick in the car. (I don't need one coz I've got a few basses already, but I reckon a cheap one for backup would be a good idea...that way if anything happens to it I'm not gonna be crying over it!)
Our guitarist has broken strings and had to change a few times, the only thing about a backup is its something else to possibly get nicked when at a gig. I may get a cheap squier bronco or something to stick in the car. (I don't need one coz I've got a few basses already, but I reckon a cheap one for backup would be a good idea...that way if anything happens to it I'm not gonna be crying over it!)