All irrelevant hogwash, as CK uses cartridge bearings. But since you asked, I have an old Stronglite threaded headset with aluminum cups and needle bearings, and it still has steel inserts for the race surfaces. Needle bearings are far less susceptible to brinelling, as they provide a line instead of point contact that balls make, which reduces the stress, however, it still seems foolish to use aluminum as apparently FSA does. The problem with needle bearings is that they are extremely difficult to adjust, which is why most manufacturers prefer to use ball bearings for headsets.