I ran an informal survey of my bike collection (some 20-odd frames a few years ago), and almost without exception, the ones with longer head steerer-tubes were the one that had pitted. Nearly all the bikes are 1973-74 vintage, except for the 1998 TREK (pitted after < 4k miles.)
So I believe that a long flexy steerer tube (or flexy head tube) is a necessary condition to have pitting. Kurt, what sized frame do you ride? Also, the cinelli, even if it was small, might have a particularly thin gauge of steerer or head tube which might have helped to contribute to the pitting of Jeff's campy headset.
I believe that more ball bearings helps. I believe that it makes no sense to keep the ball bearings a constant distance apart. I think it's a good idea to remove the retainers and run with 1 extra bearing to keep from stressing just a small portion of the headset races, and to increase the load-bearing surface by ~5-6%.
And I believe that Chas. Colerich's suggestions ("All these procedures will be for naught if the races have not been properly hardened") are also very insightful.
- Don Gillies
San Diego, CA, USA