title: CompositeWPF: EventAggregator - when to use?
body: <p>I've been looking in to the <a href="http://www.codeplex.com/CompositeWPF" rel="noreferrer">Composite Application Library</a>, and it's great, but I'm having trouble deciding when to use the EventAggregator... or rather - when NOT to use it.</p>
  
  <p>Looking at the StockTraderRI example, I'm even more confused. They are using the EventAggregator in some cases, and "classic" events in other cases (in for example the IAccountPositionService interface).</p>
  
  <p>I've already decided to use it for communication with a heavy work task, that should run on a background thread. In this case the EventAggregator offers marshalling of threads behind the scenes, so I don't have to worry much about that. Besides that I like the decoupling this approach offers.</p>
  
  <p>So my question is: When I've started using the EventAggregator in my application, why not use it for <em>all</em> custom events?</p>