The auto rim is just a case designed so that you can use it in a .45 ACP revolver without using moon or half-moon clips to extract the cases. The .45 ACP is rimless and without something for the extractor to catch, you'd have to punch them out with a dowel.
The .45 ACP is surprisingly accurate in a revolver considering that it wasn't designed for that. As far as using it for self-defense, there's no good reason not to. In fact, a .45 ACP revolver with moon clips is faster to reload than a revolver using a conventional speed loader. The .45 ACP is a proven-effective self-defense cartridge. In selecting a large-bore revolver for self-defense, I'd put the .45 ACP revolvers at the top of the list.
Oh, yeah...Almost forgot to mention; yes, I do own two of them and used to own another and there's nothing about them I don't like. Basically all the good points of any revolver with the added advantage of faster loading.