I never owned a Dan Armstrong, but back in the early 70s I had the the hots for one of these real bad. All I can remember from the time I finally got my hands on one, is that I was a bit underwhelmed. For starters, I was bench pressing about 300lbs at the time , and the thing I remember most about the DA is that it was too heavy for my tastes. They had a nice feel and the sound was pretty good , but nothing to jump up and down about. The changable pickups sounded like a great idea to me, but that was something else that was really nothing to jump up and down about. It wasn't anything that you couldn't get out of the tone control on most basses and/or a bump on the EQ of your amp. As someone mentioned, kind of a smoother version of an EB3.
If you are a Gibson lover, this may be just what you're looking for.....but they're fuggin' heavy.
Rick