After following all the various (albeit limited) offerings for 2 piece rotors for Akebono brakes - I've concluded the current development by Racing Brake to be another option (considering weight savings, quality and price) I presently have a set of front RB two-piece rotors and the quality of the rotors is outstanding.
They are in development for
rear two piece and have a current Group Buy that includes discounted fronts.
Here is the sign up list:
Infiniti G37S Rear two-piece rotor - RacingBrake Forums
If you are interested get in now - the price break ENDS SOON!