All of the reports thus far on 1.28 gpf Totos are positive. There seems to be no difference. Toto is coming out soon with .8 gpf toilets that reportedly will also function just fine. I think the thing that many folks just don't realize is that Toto engineers are working very hard to design low flow toilets that work. They don't just tweek the old flush valves or add some fancy pressure tank to the old designs. I believe I'd go with the 1.28 model.