bearings
I have no experience with ceramics, but I would think if there was a benefit to them the Nelsons, Jetts, etc. of the world use them.
BTW, a worthwhile upgrade for most engines are the bearings that are sold by Performance Specialties. Same Swiss made units as Nelson uses. They have proven to be more durable than the originals in my Rossi .53. And as to smoothness, these are the best I have felt.