There certainly wouldn't have been one had the Royal Commission recommendations been adopted in full, by a Labour Government, which instituted the Royal Commission in the first place.
If I had a vote, I'd vote no in a referendum. For the reasons outlined succinctly by Not PC.
However, for the likes of Jordan Carter, Idiot Savant and the Standard to lobby for a referendum smacks of stinking hypocrisy. These promoters of big local government didn't even raise a peep when Labour, the Alliance and the Greens let local government off the leash in 2002.
More fundamentally
If the Opposition's only concern about the mega city are:
1. It should have race based political representation (saying that non raced based representation "shuts Maori out";
2. It should be subject to a referendum.
and if National and ACT are happy to create a mega city with the power of general competence (power to do anything).
Who the hell is against the mega city and wanting LESS local government for Auckland?
It all comes back to Libertarianz. Read the Libertarianz detailed policy on local government - after all, it's the only policy around that is substantially different from the Labour/National/United Future/ NZ First/ ACT/ Maori Party/ Progressive idea of a mega city for Auckland (as these are the parties which support the current government and supported the last one for calling for a Royal Commission).