I have been looking at the Sequence 750 mainly for a closed loop! As “Louey” stated it won’t help out that much on the electric coast! However 220-volt pumps will use ½ of the amps of a 120-volt pump. Amps create heat & the higher the Amps the more the heat is created. The higher the heat the faster things wear out! So a 220-volt pump would be more efficient to run & would save you in the long run.
Yes, high voltage pump is more efficient due to the reason dwall174 mentioned. This is why heater is more efficient at lower voltage.... more heat per watt.
The issue of having a 220V pump is that the efficient may not justify for the extra work it take to get it to work with other 110v applicances.
There are transformer and invertor for that. Need to make sure they are of high quality to power the pump 24/7. It is a real hassle unless you just can't find the regular 110VAC pump. Some household may have 220V in the laudary/heater/kitchen area, but you should check with a electrician before plug into those... I have no clue.