I replaced two of the three toilets at my mother's house with these dual flush toilets. The city utility offers a generous rebate for installing dual flush toilets, so we almost made a profit installing them.
Installation was somewhat more complicated than I anticipated. Nothing a professional plumber would have trouble with, but I was a little surprised to have to drill holes into the concrete subfloor. Ask your plumber to glue a strip of rubber sheeting (or something similar) to the underside of the base, especially if the floor is not perfectly flat. This will prevent wobbling and chipping.
This toilet has a violently powerful flush. The 1.6 gallons are in and out of the bowl in about a second, maybe two. Those turds don't stand a chance. Even the 0.9 gallon low-flush option is vigorous enough for a medium-size duce.
I have two operational complaints :
(1) All toilets have the turd-stickage problem, but this model is worse than typical. Get yourself a small toilet brush, and keep it handy. I've never understood why toilet bowls aren't coated with teflon. Maybe an ocasional shot of Pam cooking oil would help keep things sliding along.
(2) Make sure the tank lid is aligned properly, or the buttons can get stuck in the "on" position. This will let the whole tank drain into the bowl, and waste a bunch of water.