Dual position, 2 bolt.
Infinitly adjustable tilt. Oval internal hollow in the Kalloy style which saves gobs of weight. On one bike I hacked off a few inches off to leave 110mm insertion & saved weight over the OEM carbon SLK with indexed tilt that I could never get quite right.

...Oh, & now I can ride for hours in the drops or choose aero bars if I want to.

The main factor is how eccentric and idiocentric the target demographic is.

Assuming you meant idiosyncratic, and yes!

When would you not need a carbon seatpost? Any time you have more than a few inches of seat post showing, carbon is the way to go because of better shock absorption.

My bike with the Campy post was stolen about five years ago, and I was incredibly frustrated by posts with clicks where my preferred adjustment was right between clicks until I got my new Trek, which came with a really nice two-bolt infinite adjustment post. The ones with clicks weren't really better than the stamped steel POS that came with my first Sears bike in 1960, just fancier. I don't understand how they can sell one-bolt posts with serrated adjustments except that maybe people don't know any better because they haven't been able to find a nice one with infinite adjustment.

Both my Thomson and Kalloy seatposts work that way. I didn't know there were so many designs! They look like this:

That one does not look like it can adjust fore/aft and tilt independently. It’s a one-piece top clamp with bolts on either side. It’ll micro-adjust, but I do not see how it could hold the rails while tilt is adjusted or hold tilt while fore/aft is adjusted.

The bolts are actually front and rear. To adjust the tilt down in front, loosen the rear bolt 1/2-1 turn, then tighten the forward bolt. Reverse the direction to raise the nose. You haven't loosened the clamp enough for the fore-aft adjustment to slip. If you want to adjust fore-aft, loosen either bolt enough for the saddle to move, locate the saddle where you want it on the clamp, and tighten the same bolt -- tilt will return to the same place it started.

Right, but that is not 2-bolt independent tilt and fore/aft adjustment. That’s a good 2-bolt micro-adjusting system.

I’m sure you understand the difference, but for reference, if we go back and look and look at the Forte post linked above, we can see one of the bolts controls only tilt, and the other bolt controls rail clamping (fore/aft), allowing independent adjustment of either.

Adjustments are easier with 2 bolt. 2 bolt makes micro adjustments of saddle tilt a lot easier, and also makes it easier to loosen the clamp enough to slide the saddle fore-aft without accidentally altering the tilt.

Also SOME 1 bolts don’t let you make miro adjustments to the tilt but rather have notches on the tilt adjust that you need to choose between.

FIFY.

In my experience, 2-bolt designs like those found on FSA SL-K or Ritchey Classic (both of which I’ve owned or still do) do not make adjustments— either macro or micro— any easier, but I believe they spread the clamping force over a bigger area and grip the saddle rails very securely.

fify

I like the Fizik design fwiw. I guess you could call it 2-bolt (?) though one which adjusts the tilt amount is a thumbwheel, so you only need to use an allen on one bolt. Nice long platform that's easy on the rails and compatible with oval or round rails.

I prefer two-bolt saddle posts.