I'm coming a bit late to this thread, but I was noticing that my toilets happen to be of the 1.6 gallon/flush variety, yet in four years of living in my house, I've never once had a flush gone wrong.

Turns out, my toilets are made by Kohler. Looking inside the tank, I didn't see anything particularly fancy. The floats are the modern round type that moves vertically on a pole, rather than the older ball on the end of an arm.

When you flush, the bowl drains in four seconds flat, and then starts refilling. I think that's part of the trick to making low-flow toilets work properly. While I'm not completely certain, I think I have Kohler Wellworth toilets, which use their "Ingenium" mechanism. Check out their animated flush.