The bearings in CK headsets are without doubt the best I've seen, as per most of the comments above they cope well with neglect and seem to last forever.
…but the lack of a wedge in the topcap means that you are hoping that whoever made your forks works to the same levels of precision with the steerer tube that CK do with the cap, which they probably don't. One guy I know had a creaking front end that only went quiet after he greased his top cap and steerer.
It always makes me chuckle that they talk about how precise the whole thing is but rely on an soft, bendy, deform-with-age o-ring to take up the gap between the cap and the fork.
I'm quite happy with my (non OEM) FSA orbit extreme pro, 5 years old and been in 3 frames, not felt the need to regrease it yet and no play creaking or rust . 😛 Just don't get me started on Cane Creek.