One of my loos has a dual system and the other loo is of the old, traditional and reliable type. It works perfectly.
The two-choice mother wastes a lot of water. I have been driven to a nervous state now where, every time I flush the thing, one half of the switch or the other, I end up having to wait until everything goes silent just to confirm the device has not jammed, as was it's wont, and which, undetected, ran through hours of wasted water in a land where water is both expensive and scarce.
Like I say, things often improve without getting any the better.
Rob