We replaced our two 1970s era water guzzling toilets with these Kohler units two days ago, and we couldn't be more pleased. I am amazed at how much better they work than our old ones, and using about one fifth of the water. I don't think we've had to use the 1.6L option at all - the 1.1L is very effective. Very well designed. As well, they were delivered well within the estimated dates, and the shipping boxes are Sustainable Forestry Initiative certified. I'd buy Kohler again, and from Wayfair. Very happy customer.