While I was quick to point out that my refactoring of my services end up being a little bit painful on the Swing Heavy-client side, when it came time to refactor my web-services client (currently a series of dedicated servlets used by my mobile devices) it was surprisingly a clean update. Why was this? What lesson can I pull from this. The main one was that the web-services code was very specific in its function which was mainly to parse the query parameters and marshall the appropriate calls to the service to obtain the results. Since I already had tests around the services calls, the main work I had to do with the refactor was re-insert a lot of the XML JAXB annotations to produce the appropriate XML output.
As an aside, while looking at MoXY with EclipseLink, I noticed their tools to assist in providing a true WebServices implementation. This might be an area to look into adopting (in providing a true JAX-WS implementation).