I have Thomson "Setback" (read: intentionally bent) seatposts on two bikes, one 27.2 mm and the other 31.6 mm, and they have been great and worth the extra cost. The saddle angle adjustment is very easy and secure and, since they are a one-piece design, there is no possibility that the saddle clamp will separate from the post.
As to bending a 27.2 mm, or even thinner, setback seatpost, I've never done it or know anybody who has. It would take a very heavy rider hitting a huge bump and that would probably damage more than just the seatpost. And, no, most stuck seat posts aren't bent, they are corroded.