In my case, I have been using a regular marine sextant for a couple of years and a few months ago I got an A12 and recently a Mark V both with artificial horizons. (the Mark V have both artificial and natural horizons)
I have tested both on land taking sights of the sun, moon, planets and starts in different location in Florida, Spain and Argentina. The A12 worked fine with errors between 3 and 8 miles, and the Mark V worked even better with errors between 2 and 6 miles compared to the real GPS positions.
Considering that both the A12 and the Mark V were built in the 1940’s, I would say that the results were quite satisfactory.
The great thing about a sextant with artificial horizon, comes at night because you can take sights of the moon, planets and stars (and a combination of them for a more accurate fix), any time at night and not necessarily during nautical twilight.