Using the UI edit feature is by far the quickest and simplest way of editting Dashboards even if you need to revert to YAML within the Views or Cards for customisation but this removes the ability to use !include to replicate a Dashboard across views.
The work-around seems to be to copy/paste the YAML but then any changes would need to be made across both Dashboards which seems clunky and overly complicated.
I would like to see a facility for duplicating a dashboard easily, either by opening up the UI file structure so editting in YAML is possible (much like you can edit Automations in YAML and use the UI) OR as an option within the UI.
A build on this would be the ability to replicate cards across Dashboards but suspect this would be more complex to achieve?