Having both basses plugged into the A/B box didn't really save any time, but it did add to the potential tangle of cables on stage. Having only one cord for either bass makes more sense to me. Less chance of a cable getting stepped on, or tangled up in the singer's feet and pulling the bass out of the stand.
The real key is being able to swap basses fast. I use the same strap no matter which bass I'm playing, and the basses all have the Dunlop Dual-Design strap locks. Have a GOOD stand which for me means the Ultimate stand that suspends the bass by the headstock. Solid, reliable, and gives me lots of options on stage for where to put the two basses. I don't like multi-instrument stands because they're so big that you have limited options for tucking the basses in between amps so they don't get knocked over.
And, I don't alter my amp settings for different basses. My amp's job is to give me what my bass sounds like so I switch from the P bass to the Lakland fretted 4-94 to the fretless 4-94 and expect the amp to give me what THAT particular bass sounds like.
jte
This is the correct answer. A/B boxes are fine but completely unnecessary.