1. I wasn't intending to make it sound like you should substitute all your Lists to Sets as I am well aware of the differences between them. I was trying to convey that on some specific cases Sets are faster than lists, whether if it's obvious or not to everyone, I don't know.
2. Yes, you can use .get(), I was trying to demonstrate the idea of EAFP, and thought that the dictionary snippet might serve as a good example, we probably disagree.
We are open to any feedback,