the ability to use mulitple ls's is a good idea however i foresee issues when it comes to end game,
if SE implement an arena like dyna into FFXIV its simply not going to be practical (esp when server population grows ) to have 5 different ls chats going on.
I know it is currently possible to turn off selected ls chat from being displayed but because you are still visable in the ls ppls still try and talk to you,
I think you should only be visable as online under your selected Active LS and maybe a /sea all function for all other game player!