title: Entity CodeFirst EF6, EntityData string id
body: <p>Have started to use Entity Code First with Azure Mobile Services and have met some issue: </p>
  
  <p>For using TableController with Entity objects I need to derive each of them from EntityData class, that provide string Id field!</p>
  
  <p>I used to use int, long and even guid instead string for id, so...</p>
  
  <p>What is benefits of this?
  What about insert operation and what is the best practice for this?
  What about performance for string id?</p>