Well, let me put it to you in real savings terms that I will see. When running my pool previously, I would typically leave my VSP set to around 2000-2250 RPMs to get the skimmer, suction vac and SWG all happily moving along (as well as run the spillway 1 hr/day). That would correspond to an electrical usage by my pump of about a kilowatt (900-1050 W). I would run like that for a couple of hours per day (4-6hrs/day) because it was too much of an inconvenience to run the cleaner separately for an hour or two at high speed with the valve all the way on the suction port, then kick that down to a slower speed and go out to the pad and manually adjust the valve back to the skimmer. There was/is no automation on the 3-way that controls the skimmer/suction port split, so it would be a daily manual exercise....not gonna happen.
Now, with the valve totally on to the skimmer (MD is tied in series unfortunately

), I set the VSP as low as 1600RPM (I don't know the true floor value yet for the SWG as I need to clean my filter) and just run it that way. I kick it up to 2500RPM when the spillway activates (I only run the spa spillway for 1 hour per day). So, for most of the day now, my pump is running at 1600RPMs which is about 275W of power.
So,
(1 - 275/1000) x 100% = 72.5% reduction in pump power consumption.
[EDIT]
So, I should add that the robot uses about 250W of power and my plan is to run it three times per week. So, net savings on the days I run the robot is
725W - 250W = 475W
[END-EDIT]
Now my electric rates are not too high ($0.11-0.15 / kWh) so I don't ever see myself recouping the cost of the robot before it will likely need some major repair (warranty is 24 months bumper-to-bumper and motors/power supplies are typically $300-$500 to replace, power cords are ~$50-$100). But, it is nice to know that I'm running my pool pump a lot less.
And, truth be told....[EDIT]
those ...
apparently there are those who are watching for grammatical errors 
[END-EDIT]
THESE robots are pretty darn cool to watch!!!!