The old freebsd-update system (which I'm still using on almost all my systems) created a new boot environment when it installed a patch, but pkg doesn't. I understand why; it's not like pkg knows that this "pkg upgrade" is upgrading base, necessarily, but it might be nice to add an option to pkg to create a boot environment during pkg installation/upgrade.
Also, the errata notices give information for performing a binary system update using freebsd-update, but don't provide instructions for doing so with pkgbase.
Also, the errata notices give information for performing a binary system update using freebsd-update, but don't provide instructions for doing so with pkgbase.