thanks, that’s it. Still unsure which is best to use for minimal disk usage, but think it is likely down to old published content that needs removing, maybe
“Content Only” and “Complete Mirroring” should have about the same disk usage
“Additive” can have a higher disk usage in scenarios, where the upstream repository regularly removes old package versions
If disk space is a serious concern, you can also take a look at download policies. Setting repositories to “download on demand” will limit their growth in disk-usage to only the packages that are actually used at your site, though depending on your exact situation, that can lead to problematic situations (e.g. if you have CVs with long “lifetimes” and upstream regularly removes old packages, the package might be gone upstream when a client requests to install it, resulting in an uninstallable package).