It's not always an option to host and manage a registry, some parts it's easier for the customers to rely on a registry service like quay, in which case it can

It's not always an option to host and manage a registry, some parts it's easier for the customers to rely on a registry service like quay, in which case it can make a difference for some images to think about layering. But you are right, s3 is fast and that's one of the reasons I'm glad Deis moved to support s3 out of the box.