I have no problem with lose ball bearings, aka cup and cone. They are probably just fine for adjustability and durability. However, if one has cartridge bearings you definitely get some speed increase by going to ceramic. I have had cartridge bearings fail. A bearing will lock up, and almost instantly the ball spacer is crunched and all the balls are crunched together and the bearing won't turn. So you either service them, or periodically replace them. I choose to service them, and the only specialized tools I use are a rubber mallet, and a dental pick to get the seal off.