We use domain mapping plugin simply for the very basic domain mapping function which we realized can be done simply within Core WordPress. We do not sell domain names so we don't need any of that type of function. For this very simple need, what is the benefit of Domain Mapping plugin over simply using WP Core? We have found the plugin troublesome in the past and are not sure we need it. We are trying to trim plugins where we can so streamline our service and performance.