If you have good internet connection it's usually downloaded a lot faster. We have switched the nixpkgs version in that version, so a lot of tooling had to be redownloaded. E.g. in our getting started video we install it on a fresh empty macbook: https://www.youtube.com/watch?v=PLl9Sjq6Nzc&feature=youtu.be The full download there takes around 9 minutes on a slow home office internet connection (it's speed up in the video, but you can see the real-world time at the top right).

We mainly added the warning in that release because usually the update process is very smooth and takes only one minute, e.g. see this tweet: https://twitter.com/mittie/status/1322574176792825861