By default we do not source nat the client ip address.
But if the sorry server is at a remote location, you will NEED to do source nat for the connection to work, otherwise the sorry server will respond directly to the client bypassing the CSS and the client will not appreciate seeing a response from a different ip than the vip.
You could use a redirect sorry server, so that a redirect response is sent to the client which does open a new connection directly with the sorry server.
Gilles.