We’ve only had one sample of Token’s Tiramic ceramic bearing bottom bracket to play with, but so far it’s not bad.
With titanium nitride coated bearing races using super hard, super smooth ceramic balls, it’s certainly silky and light to start with. It’s a very tempting price for a ceramic bottom bracket too.
Keeping it smooth depends on regularly popping off the basic seals and cleaning and regreasing the bearing faces. We had to do this a month into winter when early grind set in, but it’s been trouble-free since.