My Ti Cx came with an 31.6mm alloy seat post. I tried a 27.2 carbon one with a shim which definitely feels nicer. Now its time to buy one for the bike. It sort of feels better to avoid the shim but does a larger post feel similar to the smaller one?
Alternatively has anyone tried those Chinese ones on ebay?

Got a couple of carbon 31.6 posts, one on my ragley mmbop (SDG) the other on my road bike (3T) yes big difference cuts the buzz out and feels like your running bigger tyres/lower pressure. I didn’t think it was that big a deal until I swapped back to an Ali post on the ragley I found I was hovering out of the saddle on smaller bumps. Hope this helps!

Bugger. I meant has anyone tried the Chinese Ti ones on ebay?

I’ve got an Exotic Carbon on my C456. It’s been fine. Can’t comment on the ride quality as I’ve never ran any other post on that frame, but the ride (on the whole) is comfortable

I used to have a Raceface Next SL, which was lovely, sold that with a frame and now got a cheapo Hylix which is equally lovely, and lighter. Neither makes any difference to the ride quality that I can feel. Sticking an alu post in a plastic shim does make a difference IMO. (in the 90s you could probably sell it as some sort of suspension innovation 😉 )