One of the other advantages of the GE is the other airlines included that aren't available with the OWE. This is especially useful for the South Pacific, where you can fly from Easter Island to Tahiti and then on to NZ or Aus. It also opens up options with Air Pacific to explore other islands that are again out of reach with the OWE. With Gulf Air included too there's the same flexibility within the mid-east that isn't really present with the OWE as well (though I'm not so familiar with that part of the world myself).

Overall I think that's the main benefit, added flexibility in some areas that the oneworld airlines are weak in, and as stated before, the possibility of utilising additional segments within the one region.