Having now had this (or similar) arguments several times now, AFAICS it boils down to:
Diversity provided by any fibre path that is not going terrestrially up through the passage passing near(near being 100K or so of ) Huntly to/from Auckland to the rest of the country. Any solution solving for this would be a 'good thing'.
Several times over the last decade we have had fibre cuts which were "almost" situations on that stretch and all the carriers (AFAIK) have their cables fairly close together around this point. Not counting transmission networks fibres (i.e Transpower) etc - which for Internets/national transport don't really matter.
How this diversity happens (marine loop out around the Coromandel, or along the west coast, or a more southern landing) is irrelevant; it will solve the number one issue and concern which is Diversity/Resiliency out of Auckland to $restofNZ
My suspicion is that most of the other suggestions are trying to solve for multiple factors including presuming it would bring better international connectivity to $landpointnearyou - but all it needs to achieve is the above.
my 0.02$
-Joel
http://gplus.to/aenertia
@aenertia