I've not heard the phrase  Beater Bass before. hahaha I'll remember that.
In the past I did buy a Parker Fly guitar to take on the road touring but realised it wasn't up to scratch and sold it.
 
For most reggae gigs I tend to take my maple necked USA strat which is perfect for that music. If it's anywhere I wasn't sure of relating to secure back stage area's etc I would take my Rob Williams Strat so I guess that would loosely be descrived as my current guitar beater.
 
For bass I don't have a beater as they are all alembics, however if push came to shove It would be my Elan 4... ( But don't tell Mica)
 
Fortunately I haven't done any gigs where I need a beater for a long long time.
 
Jazzyvee

This is a great thread...
 
I think the context is rooted to the second or third sting basses that are riding the pine -- the bench if you will...  
 
However, when the time comes, and all gloves are off, and you feel like beating the heck out of a song with the most emotional veracity, and you aren't afraid of the results and after effects of of the bass, when you are done, then and only then, this bass is to be used.
 
Kinda like Hendrix setting his least favorite Fen___ on fire.

My 77 series I is the only bass I play. I've played it almost everyday since 1978 and will probably be the only one I'll ever play. My current guitar player is always asking me when I'm going to get a Fender.
 
Howierd

I gig with a Yamaha TRB-4P that shows it's age. however, it sounds fantastic. I also have a Mexi P bass and a Fender Prodigy bass that I'll drag to a gig or jam on occasion.
 
Bye,
Dave

I used to use a Mexican Jazz bass, but replaced it about a year ago with a Lakland 44-01, great neck and flexible electronics. And lighter than the Fender. It's become my primary gig bass..some of the places we play the crowd gets a little frisky after a few pops and decide to join the band..just add beer !  
 
Gary

Well - I'm not gigging now so nothing to beat on.
But my trusty old Frankenstein used to always come to gigs with me in the past (but so did my Distillate) - Frankenstein is fretless.

Those orange knobs look sooo right.
 
Here's my L-1000/SB-2 hybrid:
 

The black bass is a 1981 Ibanez Roadstar. My future plans are to re-route it for Alembic pickups and controls.  
 
I guess you could say, this bass was my beater bass. Hopefully, I could restore it back better than when it was brand new.
 
So far, I replaced the bridge. I would love to get an Alembic chrome bird to go along with it...
 
My Shorty on the other side, just sits like Bruce Lee in the background with striking confidence and support until I get my beater back online.