I don't think there is much difference between the two.
If you need a little more rinse, you can hold the handle a bit longer,
Or you can change the flapper to a blue one, and get more water later if you think you need it.
Just realized we purchased the Soiree Eco instead of the Soiree 1.6. Is there a noticeable difference in the wash. Any problems with residue left on the bowl. I'd hate to have to flush twice. Is the water spot much smaller than the 1.6. Does anyone own the 1.28 & how do you like it's performance. We still have the option of switching to the 1.6 as the toilet hasn't been delivered yet. Any & all opinions will be greatly appreciated. What's your opinion Terry? Also, rebate doesn't matter. Our city doesn't give them. Thanks