hi i have the pentax k-5 it has the same chip and is amazing at 80 iso it has no read out noise even on long exposures and 14 stop of dynamic range, have a look at this link, stacks of only 3 no flats,darks or noise reduction
http://en.astronomike.net/m/134251.html
and its high iso noise is great, this owl was shot in the dark at 3200 is
so enjoy your camera
regards brad