When I start a server as part of a remote domain I currently have to specify the remote DC in host.xml :

<domain-controller>
<!-- <local/> -->
<!-- Alternative remote domain controller configuration with a host and port -->
<remote host="192.168.1.3" port="9999"/>
</domain-controller>

would be much more convenient to specify this as a property and be able to specify it on the command line - that way I don't have to touch host.xml. With a large server group / domain that would be a real time-saver.