Unfortunately, a convincing demonstration to convince a skeptical colleague would require measuring developer productivity.

Among skeptics, I've only seen people won over by using it themselves, because when they use AI for their own work, they invest the time to review the code, understand it, and assess its quality by their own standards. That's how people learn to trust AI coding assistance.

Perhaps amusingly, I think I actually trusted it more before I started using it. Specifically because of my assessment of its quality, including things like factual correctness.