I have a custom built accurate iron 9mm that is awesome! It oozes sex appeal that no factory gun could ever ooze.
I also have a factory .40 & .45 that Accurate Iron worked the trigger, textured the grip and undercut the trigger guard on.
There is no doubt in my mind that the custom gun is sexier and tighter and probably better in ways I am not even aware of but the AI tuned factory guns are more accurate and reliable then I am.
I plan to find a used 9mm and have the same tweaks done by Mike as he did on my .40 & .45. I will use it as a practice and backup gun.
If you are just dabbling in limited then I'd say go factory and have it tuned. If your gonna saddle up for the long haul you're going to want to be riding a custom bread stallion.