Well… At least I'm not the only one…
Mine's 31.8mm – so not the smallest size they do, I've managed to shear through the bolt both times without putting a huge amount of pressure on it (as I said – I hadn't adjusted it since last time the post came out and so can't figure out how it failed this time as opposed to last time i did it up…)
It was 3 years old in all fairness… But I'd still think it should last a bit longer…
I'm considering going back to a bolted clamp like I use on my single speed… But in a triumph of Hope over experience (see what I did there?) I might give them one more go with the new design…