Sony seldom talks about DR and high ISO, but its sensors are incredibly good in this regard. Beating the low Mp Nikons will be relatively easy for the a7s, as here is a link to DxO's comparo of the a7r (with its smallish pixels) to the best Nikon can manage:
Nikon D4s versus Sony A7R versus Nikon D700 - Side by side camera comparison - DxOMark
As you can see, there is very little in it - and 36Mp versus 16Mp or 12Mp. In fact the D700 is outclassed by the a7r in all respects, and the D4s is a little better in DR at intermediate ISO levels - that is it..I expect this a7s to be something very special regarding low light, something much better than the competition.
And how good to have this camera in the 'FE fold'...and how about this:
'Currently under development, a brand-new full frame E-mount power zoom 28-135mm, F4 lens appeals to quality-conscious movie-makers. '
Nikon D4s versus Sony A7R versus Nikon D700 - Side by side camera comparison - DxOMark
As you can see, there is very little in it - and 36Mp versus 16Mp or 12Mp. In fact the D700 is outclassed by the a7r in all respects, and the D4s is a little better in DR at intermediate ISO levels - that is it..I expect this a7s to be something very special regarding low light, something much better than the competition.
And how good to have this camera in the 'FE fold'...and how about this:
'Currently under development, a brand-new full frame E-mount power zoom 28-135mm, F4 lens appeals to quality-conscious movie-makers. '