Anamnesis,

Looking at your pic, I think you can see that a zero setback post would work for you, because if you imagine the clamp head directly atop the post, there'd be plenty of flat rail section to clamp to.

As for the design and engineering question, I really don't think either design confers anything precious, and that they're merely different ways to get the saddle where it needs to be.

In the old days, before the clamp was attached to the post, offset was the rule just because there needed to be room for the clamping bracket to be tightened onto the post. In the really old days, not only was offset common, but it was 'setforward,' with the seat cantilevered quite forward of the post.

Really, when you look at vintage bikes, there was such a wide variety of designs and executions, that various and funky seatposts. I don'th think the modern setback design really popped up until the 60s, but I'm not sure. Similarly, the modern zero setback didn't really become popular until the '90s, I don't think.

Nowadays, there's still plenty of choice, as you can find zero offset clamps on bent posts that achieve setback that way, all the way up through front offset clamps and forward bent posts favored by the triathlon an time trial disciplines. Again, none are about benefits of design beyond where it positions the saddle.

VeloNews, not long ago, did a comparison test of seatpost vibration damping and other performance metrics. As I recall, it was not really possible to draw any conclusion as to whether setback or zero offset posts, as a virtue of those design elements alone, offered anything of distinction. The test did not address what I think are some of the most impotant variables in seatpost performance, namely extension and seat postion.

The feature that's probably more important to you is fine tilt adjustment, or microadjustment. In my experience, two bolt (fore/aft) zero setback posts are easiest in this regard, because loosening one bolt and tightening the other allows infinte, easy, microadjustment. Thomson Elite post is an example of this type. However, there are tons of clamp designs that may work just as well, e.g. Kent Eriksen's Sweetpost, or Ritchey's SuperLogic 1 bolt.

Typical 1 bolt setback head designs can be fussy since loosening to adjust tilt slops out the whole clamp and require two hands and some judiciously applied force to get moving, and a keen eye towards adjustment as tightening pulls down and can give more tilt than planned. I think your Paul design addresses that problem.

As a final note, I dont think you've enough extension to discern post material difference, so you're free to choose on style!

I hope thst helps!