It's not likely to be the fact that they flush with 1.6g, but the design of the toilet that is the issue. A Caroma uses a 3" trapway, most others are closer to 2". But, a lot of the issue is how smooth the curves of the trapway design are. tight turns are not friendly for large stools. For 99% of the population, a good (and by no means are all of them good) 1.6g toilet works fine. Lots of people have had good luck with the Toto Drake, or Drake II because it has a very well-designed trap. But, if the stools are very long and hard, the larger trapway of the Caroma may be your salvation. They do splash a bit, but that's better than having to break things apart and reflushing. The Totos that use the Unifit adapter have very smooth walls, and work well, too. But, they still are smaller diameter than the Caromas.