Personally I couldn't be less interested in op amp rolling. If this Reference version is his best configuration, its simplicity is its great strength IMO.
But there is still the power issue for high ohm headphones. It might have enough gain for 600 ohms - my Bithead does - but that's not the same as providing enough power to drive the cans properly (which the Bithead does okay but not great).
Still this looks to really have potential. How many years will it take to get one?