I definitely think there's merit to owning an ABG, based on my experience with a Tacoma. I agree with what many have said regarding their convenience for practice and how imperfections in one's playing are revealed. The Tacoma balances well with an acoustic un-amplified in a quiet setting. I have also played it with a vocal, one acoustic and a cajon in a small room where it kept up fairly well when played with a pick. I'm sure that there are other well-made ABGs that are comparable, although I've also played quite a few that have sounded a bit thin and don't project much. One just has to manage expectations

Here's an example I found of a Tacoma played with a pick in a band setting (the acoustics of the room, the small-bodied guitars and the not-so-heavy percussion do seem to help a bit here):
Agreed. I particularly like the tone of the instrument bronze round-wounds for un-amplified practice with a metronome or playing classical pieces, and that is merit enough for me. Yes, it is definitely a challenge to play cleanly (i.e. with minimal string noise), but I find the woody tone of the instrument very rewarding and worth the effort. This gentleman really plays an ABG well and is able to make the most of the woody tone I'm referring to (I believe he is using nickel strings strung E to C here) - it sounds neither like an electric nor like an upright, but it's a great tone in it's own right:
As others have also said, it's best to try before purchasing. I was ably to try the Tacoma before buying and bought it because I was happy with it, others may not have so happy with it.