I use sealants on two of our silver cars and carnaubas on (uhm..counting...) three. Silver can look *very* good with carnauba on it. I use KSG on my silver Mazda, and to be honest it looked better when I topped the KSG with #16.
My wife's A8 and my S8 are virtually identical, I use carnauba on hers and sealants on mine. While they look different with #16 on hers and UPP on mine, it's not like the #16 looks inferior.
Same ol' same ol' IMO...95% of it is prep and prepping silver is a royal PIA because it's so hard to see very light flaws. So that "hidden" marring..the stuff that "nobody sees anyhow" makes the light refract and that spoils the look in a subtle way.
FWIW, my wife's all time favorite look on (Audi) silver was a carnauba: Souveran. She *still* remembers how she liked that so well, and she's not the sort of person who really cares about this stuff. But she's seen a whole lot of different LSPs on silver Audis over the years, so when one product out of maybe twenty makes that sort of impression it tells me something.