I would rate the first-time setup as 5 and maintaining as 1.
The initial setup/configuration process, though well documented, still requires caution with configuration file. Once the app.yml file is there, to update Discourse later on, the only thing you need is ./launcher rebuild app.
I would recommend you start with two-container setup, which will give you almost zero down-time during update.
Extremely easy. Just stop the container ./launcher stop app and use rsync -av /var/discourse new_host:/var/ to copy the entire folder and then run ./launcher rebuild app on the new host.
At most time it’s hassle-free. If you use some old and not-well-maintained third-part plugins/theme components, you may run into trouble after performing an update, but you can disable it anyway.