The SB and AS are more or leess the same, one is non AI, the other AI, both prisms were specifically meant to be used in low light photography.
The A is the AI version of the traditional F2 with photomic head.
I personally have a F2A (with DP11 head) and a F2AS (with DP12), while the DP12 is obviously superior in low light for every day shooting I prefer the DP11.
I was happy you responded with all this info, and then i forgot to ask...
.......i do not have an SB, i have the S. The SB adds a third LED if i understand correctly, and that would be cool, i think i would prefer that over my S if i had a choice.
But, most of what i do with a 35mm involves constantly changing light.
Usually, i have an aperture in mind that i want to use for a certain look, so i adjust for exposure via the shutter speed, and i seem to prefer looking at the "old fashioned" needle in that situation than watching LED's.
I realize the SB/AS are more sensitive (maybe more accurate.?) but i seem to do OK with the older technology.
Am i reading your comment correctly, do you prefer the DP-1 over the SB/AS also.?
Thank You