title: Using mongos with non-sharded replica sets
body: <p>Is there any advantage or disadvantage to using mongos in front of just a replica set (as opposed to a sharded cluster)?  Having to specify the same replica set members in multiple apps doesn't feel right to me -- I'd rather do it in one central place.</p>
  
  <p>If anything, sharding in the future would be more straight-forward.  Right?</p>
  
  <p>Thanks in advance!
  Harry.</p>