Having to stay logged into two clients in order to chat on both servers or to talk to someone or to see if someone is online on another server makes it harder to track down people who you want to keep in contact with.

If there was a new trigger added like a @pve or @pvp at the end of command /w name for whispers then it could be possible to send whispers between the two if setup properly.

An example would be "/w name@pve your message here" or "/w name@pvp your message here"

That way I could talk to player on pvp while I'm on pvp by not putting an @ beside their name, while I could talk to the exact same person with the exact same name on the pve server by putting @pve at the end of their name, in theory I could continue to play whatever server I want while still having a conversation with someone from whatever server they want to play, even if its not the same server.