Similarly, I have used autopilot in rain so bad that I was scared to drive. It performed perfectly and was much less stressful for me.

I was fully engaged and ready to take over, but never needed to.

I'll echo that. Heavy rain, I could barely see the lines, but the car seemed to find them just fine and was driving straight and smooth.

Until traffic on the other side of the median barrier hit a big deep puddle, absolutely covering my car with a thick sheet of water. Autopilot immediately started screaming at me to take control. I already had my hands on the wheel, but it still scared me because I couldn't see either! After the water washed a way in a couple seconds, I was able to re-enable AP and keep going.