Yes. I know that Shimano says not to service them, but that didn't seem right, which is why I initially asked if they really were or not. The link I shared (http://forums.mtbr.com/drivetrain-sh...cs-497220.html) confirmed that they were serviceable once you get the plastic dust seal off (and shared some techniques for doing so). Once you get the seal off, it's no different than servicing a cartridge bearing on a hub or headset - unless I'm missing something.