I was listening to a home improvement radio show run by a plumber here in KC, and he said that the first generation low flow toilets were disasters. However newer designs do work. The key is that there was about a 3 year period where very few newly sold toilets took care of business on the first flush. Unfortunately there are still a lot of cheap toilets on the market that don't work properly. It actually took a redesign of the entire toilet, not just a smaller capacity tank. On the other hand, there are no problems with a lot of the newer, but more expensive toilets on the market.
Mark
I do have one of the newer toilets, about $100.