I have sat in various cars s550 and s450 but not sure if its about the seat adjustments or the leather type. Each model I tried with Napa and one new S450 with standard seemed stiffer but I couldn't adjust the seat and wasn't sure if it was because it was new car. The 2016 s550 with Napa was gloriously comfortable and again I wasn't sure if it was the settings or the Napa. fit like a glove.
I am looking at a CPO s450 with standard leather and really appreciate the best comfort in seats.
Is the real issue the multi contour seat that gives comfort? or is Napa leather the difference.
Please advise

The nappy leather is very soft, it seems the more you pay the softer it gets........and wears out.

there are 3 levels of leather in the s450: standard, nappa, and exclusive nappa. i have the exclusive nappa and it is buttery soft but extraordinarily durable. it was an expensive upgrade but imo well worth it.

I had the Designo nappa and yes its soft but yes it wears out a lot faster. The standard seats do feel harder and with the Nappa you do sink in more like you stated.

Is durability more important than appearance for you?

Comfort. But I bought a cpo 2018. Not many with Napa leather available and I think I got all other options I wanted.
the price was great and low miles
if it bothers me in 3 months I’ll just trade it in in a couple years and only buy Napa in the future.

I have owned 5 Mercedes in a row and never been disappointed with the newer Model
in fact usually amazed by the improvements

thanks

slight correction: there are 3 levels, but the 2 nappas available are just stitched differently from what I understand and are of identical comfort/quality. The highest level is actually the semi-aniline leather.

This guy really complains about the standard seats.