I just bring 2 basses.
The guitar players change guitars, why can't I change basses?
The sound tech in me advises against this. With PA reinforcement the low end changes enough from bass to bass regardless of how even it sounds at the bass amp. I switch between fretted and fretless, but the change is drastic enough that I wouldn't want them balancing the exact same anyway. But if the PA is set up for a Rush Rickenbacker, it'll be night-and-day heavier when you pull the P bass out. Sure you'll make adjustments at the bass rig, but for example if the sound tech insists on pre-EQ DI and is having a smoke when you switch...
