Much lower wear and slightly less friction. But they cost roughly 10x as much going from a quality steel bearing. They are marketed as being faster but it's n

Much lower wear and slightly less friction. But they cost roughly 10x as much going from a quality steel bearing. They are marketed as being faster but it's not noticeable in real world conditions. They might be worth it in some non-cycling applications (high precision motors or something). They also break if abused. Steel bearings might deform the balls or dent the race, but they will still turn. However, as long as there are people with $250 to spend someone will make a $250 set of bearings- don't forget to lube them with snake oil for the fastest results.