I am closing this thread.
Why?
Because over the years questions concerning rust prevention and the various products and methods of application is one of, if not the most common queries to appear on both this and other Land Rover forums. This inevitably means there is already a wealth of information already in existence here and elsewhere including some very lengthy discussions of the products and services quoted. A quick Google search will bring up more than enough reading material to occupy the most inquisitive of minds.