I can only give you my tested opinion as a new toto convert. I "upgraded" to kohler 1.28 gal flush in a house I just sold. We kept plungers next to the toilet in every bathroom as they clogged constantly - and I mean several times a week. In my new home, we had american standard. Flushed great, but...both toilets had problems with the inner parts. Rather than replace, I read up and decided on toto. I went with ultramax for the one piece design at my wife's request, but the flush system is similar in other toilets. We have put these things to the test and have not had to unpack the plunger yet. At 1.6 G, they are not "efficent", but they do the hard work. In my completely unprofessional opinion (based on my lifetime total of about a dozen toilet replacements) the design of the toilet aids in the waste removal. When you see the seemingly small amount of water in the holding area, and watch it flush - fast and quiet, it seems like hardly any water or force comes out, but it clears out. My opinion is that the low and deep well and the way the water is pushed straight at the well, no swirling, just a push, like water on a chute - straight and forceful- is what makes these things work.