Proper techniques for allowing many views to subscribe to window.unload?
An opinion question, always tricky;

I think we can all agree that the second approach is not KISS and requires more bandwidth to download to the browser. As far as I can tell, this will not save any memory either..

I would strongly suggest to use the first approach.

Furthermore:


unsubscribe could be reduced to:

unsubscribe: function (view) {
  this.get('views') = _without( this.get('views') , view );
}

Production code should not use console.log
subscribe could use _.union()
subscribe could be reduced to:

subscribe: function (view) {
  this.get('views') = _union( this.get('views') , view );
}