If you go with carbon fiber seatpost, you need to find carbon assembly compound as a lube. There are some pretty SERIOUS guys who will tell you NOT to use grease on a CF seatpost. I know that I had one partially seize up, and after a lot of effort to remove it, some of the surface was peeled off. I had NOT used lube (either type) when I put it in, so it came back to bite me. I am now using alloy posts, and use a Teflon grease to install them, to forestall the drama of another seized post.