i have been using the btp carbon clamp for over a month now. it's svelte at 6.5 grams
, and surprisingly, the seatpost has not slipped. i am using an extralite 'the post ul'.
back to off topic again here, but i'm a little frightful of the btp carbon clamps for my ergo levers. i feel the carbon part of the clamp is super strong, but the strength of the alloy thread and nut is questionable. having a good portion of body weight reliant on the strength of an alloy thread / nut combination is a worry, particularly if one climbs out of the saddle a lot. i opted to keep the stock ergo clamp setup, and forgo the weight saving in the name of safety.
if btp would use a steel thread piece in the clamp, this would work much better. the alloy nut would be fine threading onto this.