Namely, Less sudsing so you don’t overflow. And enzymes and chemicals that supposedly remove dirt/stink/(why you wash clothes) with less water.
Not speaking from experience with the HE4t just looking at their site, I am guessing you can save the planet by using less water and energy.
I am not sure what the cost benefit analysis is but if you have a higher capacity and are able to use less water and energy you are saving.
This may even lower the cost of energy for everything as a supply and demand issue.
Less dependence on fossil fuels. Save the planet, one load of laundry at a time.