The 6218 WeekDater is a watch far above the ordinary. The 1964 WeekDater is the immediate, automatic equivalent of the 1964 Grand Seiko hand-wind (the first automatic Grand Seiko appeared in 1967 in the form of the 62GS).
At the time of its introduction in 1964, the 6218 was top-of-the-range, the flagship of the Seiko automatic lineup. Both the 57GS/43999, 6218 and the 62GS have 35/39J movements, and it has been suggested that the extra jeweling was introduced to facilitate the day/date complication in the low-beat, low-torque movements (http://seikoholics.yuku.com/topic/911/Seiko-6216#.UMugiKU1blI).
I feel we may underestimate the complexities involved in the mechanics of a day/date function back in 1964 - Seiko specifically highlights this feature in their description of the second-generation (1964) GS (http://www.grand-seiko.com/features/history.html) and Rolex has the "Day-Date" as a flagship model in their lineup to this day.
The quality of finishing on the dial, indices, hands etc. of the 6218 is superb, equally to that of the Grand Seiko, and the tadpole regulator of the 6218b is identical to that of the 43999 movement. At the moment the 6218 WeekDater is undervalued by collectors, and in my opinion a good long-term investment together with the second-generation GS.
