Well, I didn't really have time to read thru this whole thread that's grown to 8 pages in, what, 4 days? I'm sure I'm not going to add anything that hasn't been said already, but these are a few things that have happened to me:
1. Middle of a show, middle of a set, middle of a song, my bass, my only bass at the time, gave me the finger and quit! Yes, if I'd been playing a passive bass or one with a bypass, it would've been ok, but that's not the point. A backup is not necessary, but recommended.
2. Happened last weekend: broke a string! This is, maybe, the 3rd time in 20+ years of playing that I've actually broken a string during a show. The last time, I only had one bass=show stoppage. This time, I just put it down and picked up my backup=happy bandmates & happy audience.
3. Alternate tunings: I play in a cover band and we always try to play songs in the key that they're written in, which means some stuff is in standard, some stuff is 1/2 step down, some stuff is a whole step down, and then you add in your dropped tunings and that makes for a long set with very little music if you have to keep retuning=show stoppage.
4. It's fun and somewhat inspiring to pick up a different instrument and see if you can get it to sound the way you want it to sound.
I take 3 basses to every gig. Why? Because I don't have 4...yet!

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