> In fact, you should be using Puppet or Chef even if you're > just one guy with just one server to manage. > > If you need to replace the box with faster hardware, for > example, just run Puppet on the new box, and it will (if > you have done your job properly) become identical to the > new one.

If you've done your job right with the shell script, the same will be true. The problem is that if you have more than N nodes, "doing the job right" becomes more difficult. However N is quite obviously greater than one.