I dove with the -D2s for the first time this weekend and I thought the faster cycle time definitely made a difference for my own impatience of trying to take another photo as soon as possible, where the D1s wouldn't exactly be ready but the D2s were. They also have some minor body and diffuser improvement, I personally don't care about the different knobs, the ready light is easier to see. The audio indicator doesn't appear to be working as advertised. I only hear the audio indicator when I first turn the strobes on. So far there is no audio indicator when the strobe is ready to shoot again. In fact, the manual makes no mention of the audio feature.