Scrod,
Have you ever dealt with a seat post that had its paint scrape off it into the seat tube this causing it to slip even when torqued down? This Deda RS01 seatpost is killing me. I think I just have to take it off, sand off the pain that came off (the white lettering) on the inside of the seat tube, and try again. It's slipping enough to be about 1cm a week or so of riding.