Buy the S600. You will love it. It has a certain presence and "feel" the S63 just doesn't have. I faced the same dilema a few months back and sought advice here as well. I bought the S600 ('09 leftover) and absolutely love it. Its well worth the wait.
PS Should you choose not to wait, please give me the name and number of your dealer. I will gladly take your place at delivery!
