We have 1.6 GPF Toto Supreme one-piece toilets with Power Gravity flush. I'll spare you the details, but at least in the Supreme, very little water irrigates the rear of the bowl, sometimes requiring a second flush.

Toto's "double cyclone" E-max flush design (offered in the "Eco Supreme") appears to be more effective (at least according to their own marketing claims). Had I to do it over again, I would've probably opted for the 1.28 GPF double cyclone design instead.

Go to www.TerryLove.com website. he has a toilet reviews. Most all Totos are good. Some much better than the others.

Here is a link that might be useful: TerryLove Plumbing forum/website

If you haven't already, read the other Toto thread ("Guinevere . . . looooong post"), as I just did. Apparently, some aren't happy at all with the perhaps, over-hyped, "double cyclone" performance of the Toto 1.28 GPF "Eco" toilets. Others are. Go figure.

I have a Toto Soiree and Toto UltraMax toilets. I much prefer the UltraMax with their GMAX flushing system. The Toto toilets with GMAX flushing strike me as far more efficient and stronger than the so-called "double cyclone" flushing mechanism in the Soiree and Guinevere. The water during the flush on the Soiree just gently washes down from the top lip and often requires two flushes, while the UltraMax is far more forceful in getting rid of waste.

Greg

I started this thread so now I can make my own report. We bought the Soiree about 6 weeks ago partly because I read that it could be modified to flush with 1.6 gallons if the 1.28 didn't work out. We've had a G-Max Toto Carrollton for 5 years and it's been very effective.

The Soiree at 1.28 gallons has also been absolutely fine so far and has flushed everything we have thrown at it. Like the Carrollton and all modern toilets using less water you can sometimes get a skid mark. But what I have discovered with the Soiree's Sanagloss is that if it's below the waterline it will clean up perfectly by itself with the next flush after a while.

One thing we appreciate about the double cyclone flush is that there is no normal rim, and no place therefore for dirt to hide under it. It's a cleaner bowl.

Ours is a TOTO Drake, 1.6GF G-Max, comfort height, elongated.
We've had about 1 1/2 months. Havent used plunger yet, hasnt required more than 1 flush. Our previous builder's model toilet plugged almost daily and often required an extra flush.
LOVE this toilet so far, one powerful Swooosh! and its all gone. Flushes so well, I'm noticing that I'm not cleaning the bowl as often either (yay, less chemicals!) :)

this is the greatest pic, but here it is:

I installed the Guinevere with a 14" unifit adapter about a month ago. I purchased it, with some trepidation, after having trolled through all of the internet forums/reviews that I could find. The toilet we were replacing was a very old two piece toilet, with an enormous wall mounted tank, conncted to the bowl by a chrome pipe. My old toilet flushed beautifully, but probably used 6-7 gallons per flush. I fully expected to be disappointed with even the best of modern toilets.

To my surprise, I am delighted with the Guinevere. We have never had to double flush, nor have we had to use a brush to clean the bowl after use. The Guinevere can acually be used as a dual flush. Do a standard flush for liquids, and hold the lever up longer for solids. Works like a charm.

Installation was a pain. The base is so wide that we had to move our water line. And yes, it does make trickling noises during use; but who cares. It works great and uses very little water.