Here's my take on ABGs, which is only my take on them. They are legitimately its own instrument. They're not a suitable replacement for a double bass nor something that will make a band sound more folkey or more bluegrass-y. They don't feel like a Fender bass if for no other reason that they're acoustic guitars with a string plane four to eight inches further away from your body. They will require some adjustments to your plucking hand technique. They can also be a little painful to play for hours with the sharp edge of the upper body digging into your forearm flesh.
But ABGs are also a very unique and rewarding instrument to play in situations more traditionally suited for traditional basses, which is when I like to deploy them. I kinda had a lightbulb moment about ABGs while watching a fado band in Lisbon a few years ago. After a half set of traditional fado songs they surprised me by doing a fado-ish cover of "Whipping Post". It was fantastic, especially the sound of the ABG in that context. With the Portuguese guitars and Portuguese accordion, it anchored the song.
So when I got back to NYC I started playing around with using my ABG in unlikely contexts and it kinda opened up a new world of playing options for me. I had a low-pressure demo session and took my Boulder Creek to it along with my Sadowsky J and Pedulla fretless.
The composer had literally scrawled chords and bar counts on a legal pad. My chart was an iPad photo of it. IOW, the songs were wide open for interpretation. On the final song on the session he said he was looking for a Springsteen feel. The Sadowsky sounded too, I dunno, same old/same old. The fretless was better but it still didn't pop. So I deployed the ABG.
Dropbox - 07 I Just Wanna Drive.mp3 - Simplify your life
It was six hours into a long session and the cut here is like Take 29 because of all the head rearranging. My fingers were in bad shape from the stiff bronze roundwounds. It clearly wasn't my best performance of the day but the sound of the ABG was unmistakable. It was so different that the song got reshaped around the lines I built for the song on the ABG. In the end I was at fault for about 20 of those takes (that, and a very tired drummer).
Since then I've used the ABG a lot... on Latin gigs, Americana gigs and on traditional jazz gigs where I was too lazy to bring my double bass. I even built a digital weapons platform just for my (now) Fender Kingman ABG.