One of the nice things about Exherbos take on slots is that you won't get breakage with library upgrades because you won't be able to uninstall the old version

One of the nice things about Exherbos take on slots is that you won't get breakage with library upgrades because you won't be able to uninstall the old version until all packages declared to build with that ABI (or more specifically that slot was installed and built against) are rebuilt against the new library. ABI breakages are far less painful than on gentoo.