I also think it's difficult to calculate ROI when you don't know when the ASIC is going to arrive and the other factor is the difficulty which will be influenced by any significant increase in hashing power.  At the end of the day we are all competing for a limited number of coins with faster and faster hardware.  As new faster ASICs are produced and sold the old ones will fall in price, the speed at which the price of the old ones falls will depend on how quickly the new ASICs are produced, sold and come online.  The only constant is change.   I think it's really unfair that companies are not delivering goods in a timely fashion as a few months can make the difference between profit and loss.