My beater isn't necessarily any less valuable than some of my other basses, but if I had a show where rain, damage, chips, or having to use the bass as a weapon was a possibility I'd bring my '95 MIM P-bass. It's been modded to heck and already has lots of chips and dings. Being my first bass, it's got alot of sentimental value, but it'd be the easiest to replace, repair, or find new parts for if it got damaged.
None of my basses is worth much more than $800 ( most quite a bit less) and except for my very clean '79 T-40 -which still goes out to some gigs- and a rather fragile vintage scroll viola bass I'd take any of my basses to all but the most risky gigs.
Here it is, complete with hammertone sprayed pickguard. The only remaining original parts are the neck, nut, string tree, body, neckplate and screws.