2nd world? no, not enough reason to do it, there's plenty places to do slayer, there's not a huge pk scene so dividing the server wouldn't be a good idea.
 
Raids bank? sure
 
Dks slayer cave? sure, I could see that happening.
 
Cannonballs able to be made? I'm not sure how I feel about this, no comment on it.
 
Good luck with your suggestion.