Very impressive photos. The images have a very good texture to them. I agree with you about wanting an extra stop of clean ISO. Your photo of the Harley gas cap at ISO 640 demonstrates just how good it can be when properly exposed. Too bad ISO 1250 isn’t as good. Even with the relatively fast Leica S glass, sometimes you really need more low light capability than the S2 is currently capable of delivering. Even so, I have a very hard time making myself use my Canon.
I would like to think Leica is working on a firmware improvement that would eek out better ISO 1250 performance. That is probably just a dream on my part since I haven’t heard anything about new firmware. However, I have read that Leica is working on a 30 – 90mm zoom for the S2 and I am really looking forward to it.