i just took the idea from the crock pot link and also from my dishwasher, the 45 degree cycle takes 2 hours 55 mins and the 70 degree takes 2 hours and 15 mins. i can reduce the time on the 2 by pushing a button called "vario speed" then the times are 1:30 and 1:27, the difference is water used and the speed on the pump the circulate the water. it do cost more since more water used and you need to heat more water.
of course that can not be used as a direct compare but there is a bit of it, lower temp but run longer, 40 mins in difference but the amount of water is the same... so we lower the temp but run 40 mins longer to get the dishes clean. of course there is a point where the math does not add up any more, ie where the longer run is not justified against electricity used to keep the water at 45 degrees.
of course it raise the need for a google search on how to figure the break even point