Just curious about people's approaches this one. The general wisdom (which I have myself doled out) is that a professional should certainly consider bringing a backup to important gigs where downtime would be an issue. I sometimes bring a backup guitar to my guitar gigs since guitar strings do occasionally break, but I can't remember ever needing a backup for a bass on a gig as long as it was maintained well (and had an active/passive switch if active). I do have a somewhat complementary matching pair now (active Dingwall Super J5 with rounds, passive Dingwall Super P5 with flats, both vintage white with rosewood boards and tort pickguards). I do bring spare strings, backup cables and a DI.