I have used the Elita One carbon seat clamp and I would not recommend it.
It states on it that you should tighten to a max 6nm which I duly did and it was way too little to stop my seat post from moving. I attempted to slowly increased the torque past that (to a still not particularly high 7nm) and it snapped. So clearly a proper weight weenie item right at the limits, use at your own risk etc.
Which would be fine but for the fact it was only 3grams lighter than the stock alloy clamp it replaced.
IMO the gains are way too small to be worth going weight weenie here.