Our house is 17 years old, and came with some of the earliest (and cheapest) versions of water-saving toilets. Performance was abysmal. We first tried the original Kohler Wellworth, which offered only marginal improvement. Next we installed an earlier-model Toto Drake (1.6 gpf), with a 3 inch flapper valve, which has provided excellent service with few clogs, although a little noisy. Installation was straightforward, and the parts have held up over time. The bowl stays fairly clean, but could be somewhat better (4.5 stars?). Then we installed two Kohler Cimarron "Force Five" toilets. The tank mounting system for these Kohlers is a little different, and eliminates two possible points for leakage as gaskets age. These also have a 3 inch flapper, and have performed well. They seem slightly less noisy. These also stay reasonably clean. For a more complete flush, we've had to hold the handle down for a few seconds on all of these models -- the Wellworth for as long as 7 seconds (it has the older 2 inch valve). I replaced the flapper on one of the Cimarrons with a "Korky" brand model that is adjustable (the vent hole in the side of the bulbous portion can be made smaller or closed completely), and performance was somewhat improved because a somewhat greater amount of water passes through before the valve closes.
The Toto Drake II was purchased to replace the Wellworth, in our guest half bath, due to its mediocre performance (Here, Aunt Irene, take this plunger with you -- "); it has the same internal tank configuration, but uses only 1.28 gallons per flush. In addition, the traditional toilet bowl rim with a series of tiny holes has been reengineered. The bowl is now rinsed by a double vortex of water provided by two horizonal outlets at the back of the rim. Although this is early days, it seems to work VERY well. I have seen a few reviews expressing concern about the amount of tightening the mounting bolts require to seat the tank on the bowl, but personally did not find it to be an issue. "Stubby" wrenches or a socket set work quite well. Just alternate sides frequently.
In terms of performance, a quick push on the handle provides a briefer flush that uses less water, but seems sufficient for liquids. Holding the handle for a two-count essentially empties the tank and provides a more powerful flush. "Dual-flush" toilets seem to offer little benefit in this situation, unless you're in a truly water-starved area. The noise level is acceptable, seeming slightly less than the others. At two seventy-five from an on-line source, including shipping, this was similar in price to the two Cimarrons and about a hundred forty-five cheaper than the original Toto, locally purchased. It was exceptionally well packed in double boxes filled with foam, and arrived in less than 3 days. The ceramic portions were marked "Made in USA," but third-party websites note that this product can come from multiple sources. Toto's "Ultramax" line is listed as all made in USA.
UPDATE: We have had it about a year now, and have installed a second one, replacing one of the Cimarrons (which was defective). Couldn't be happier with them!