The getting started guides using docker (both the single and multi-nodes examples) are not meant to be used in a production deployment. They are meant to provide the lowest friction path to getting a cluster running where you can experiment with the Kubernetes concepts in a running cluster.

If your choices are between running a variant of the docker multi-node configuration and bare metal on Ubuntu, I would definitely recommend running on Ubuntu. See the Kubernetes Deployment On Bare-metal Ubuntu Nodes getting started guide.