They weight the flapper down on the 1.28.
They flush fine with the lower 1.28, but if more water is needed, then holding the handle down a bit longer gives you that.
In Seattle I still have some CST744E Toto Eco Drakes for $20.00 less until I have to reorder.
Then they go back to same/same.
I also have the Drake II CST454CEFG for $35.00 less until I run out and have to reorder.