Double cyclone is Toto's latest invention...it does work by giving better bowl wash. Not to say that the old ones are bad, just that the newest version is better. They got the extra water savings by more accurately timing the water refill. All toilets somewhat overfill the bowl...the new ones do it less. The initial volume to flush remains the same, so minimal if any difference. Comparing my old toilets with the new ones that have Sanagloss, yes, it is worth it. I have IRB, and it takes weeks longer to build up and is much easier to clean on the toilets with Sanagloss than the old ones without. Essentially just a quick brush removes the ring, whereas in the old ones without Sanagloss, it came back quicker, and was harder to scrub clean.