Friction facts tested a lot of BBs and the winner was a steel bearing designed for track. I firmly believe that there is no real world advantage in performance between high quality steel or ceramic bearings.
On track, you can lube bearings with just oil and reach outstanding smoothness with any bearings, steel or ceramic. At the end, the difference is, according to my experience, close to zero.
On the road, you cannot lube with just oil except for a TT maybe... The grease is the key and then:
-the gap between jockey wheels will be significant (lets say 1-2W for a set of ceramic/Dura Ace) because the ceramic is not subject to rust and has limited lube on bearings, and the Dura Ace, made of steel bearings has a thick grease.
-ceramic bearings for BB and hubs are usually different, they use different features. Manufacturers of steel BB use a bad quality grease that has a major advantage, it's waterproof and the longevity of these products is good. But ceramic manufacturers can use better quality greases, anyway if their grease goes out, the bearings will not rust.
So, at the end quality ceramic bearings can be used for a longer time than steel bearings with a better smoothness, but the reason is more on the quality of the materials than on the difference of smoothness itself.