50%+ cycle time reduction on 300mm

ISMI’s recently published factory simulation shows that great cycle time gains (on the order of 50%+) can be achieved with 300mm.  It seems the ISMI decision last summer to move forward with 450mm didn’t include this information.  Was the decision premature? SEMI’s recently released study claims a 50% increase in cycle time for 450mm.  Does this mean the net cycle time gain for 450mm is near zero?  ISMI has yet to publish an economic analysis for 450mm so a comparison of cost/benefit has yet to be done by the chipmakers, so expect the debate to continue… Comments?