“We’ve seen Rand’s ideal Objectivist society operating in Galt’s Gulch. How well would it work in the real world?”
The problem with Objectivitism in regards to humanity is human emotion and frailty. Leaving aside the atheism of Ms. Rand, Objectivism cannot work in the real world.
Rand appears to assume that people can be raised to be objective in the pursuit of life, liberty and happiness.
Humans are fallible and venal along with some being outright evil.
No matter how objective one would like to be, emotion gets in the way.
In Atlas Shrugged, Rand does an excellent job of portraying just how much government can screw up business and screw up a country.
Unfortunately, she also shows her limitations when it comes to people and emotion.
And yet capitalism, based on the twin fuels of greed and envy, works just fine. Those twin fuels are two of the seven deadly sins, so human emotion and frailty are a part of what makes it work.