I changed the front and rear carriers because they needed to be changed. The front cam retainer as well.
At 46,000 miles, the front and rear bearings measured JUST within specification. It didn't seem wise to reuse them if I plan on riding the thing 10,000 miles / year....which is exactly what I intend to do!
All the bearings were still usable (sizewise), but they were dirty. You can see what the lack of an oil filter will do to the bearing surfaces. On the other hand, the cam and crank were in fine shape.
So the bearings did their job. Nothing failed and I probably could have thrown a battery in it and ridden it for another 20,000 But they were due for retirement.