I don't know how you come to this conclusion as the Xeon E3 has a lower TDP than the current high endThis new iMac will have to be thicker.
This condiguration will run cooler and quieter , and be more reliable (ECC) memory at about the same performance level of the top end 6700k.
If they do upgrade the drive speed and put in a much better GPU, it should overall be a very good system.