That's what I was thinking too. It would work for all servers if you wanted to just talk to a group of people without everyone else hearing. The only thing is that chat would be about two times a quiet with this if people used it frequently.
You could use the commands that I listed earlier and instead of /rp ..... Maybe /group ...... Either way what ever you want to call it, It will still have the same purpose and slow down chat.
Well u could make it so people can't do /rp <name> chat unless the r added to the rp and make it so mods can see it