@Adam: If you have an apport hook for a binary package, it belong to the binary package that it is for. It will be only used if you report a bug against this binary package. In contrast a _source apport hook will be used for all binary packages that are build from this source and therefore should be put in one binary package that's always installed if you install one of the binary package.
@Mathias: Ok, that's reasonable.
@Adam: If you have an apport hook for a binary package, it belong to the binary package that it is for. It will be only used if you report a bug against this binary package. In contrast a _source apport hook will be used for all binary packages that are build from this source and therefore should be put in one binary package that's always installed if you install one of the binary package.