Ok, stupid question of the day- why should a bomb sight be more accurate by night than by day? My simple mind cannot understand the logic of that.
Probably my bad use of English... the Mk XIV was equally accurate during night and day and was designed for dropping sticks and clusters of weapons at night when main force was bombing visually on flares often dropped by use of electronic targeting aids - quantity of bombs on target area over quality of aiming was the order of the day (think shotgun). Something more accurate was needed for single bombs in daylight and hence the use of the SABS for this tasking. No doubt, cost, rate of manufacture, and ease of setting up the sight was also a factor in which system to use, although I believe that targets were more difficult to find when using SABS at night. Also note that both bomb sights were integrated into the aircraft systems and could not be easily transferred - hence their use by just IX and 617 as the 2 precision bombing squadrons in their "special" modified Lancasters.