Originally posted by Fl_Gulfer I hope Pentax can get there ISO performance up.
That would indeed be nice. But to really boost the low-light ISO into the realm of the D800 or D600, as DxO note, a larger FF sensor would be needed to catch more light, whilst preserving the same pixel quality of the K-5. So unless Sony makes a break through in it's APS-C sensor tech, or Pentax does a FF, low-light ISO at K-5 levels may be as good as we can expect for a while from Pentax.
Having said that, the FF 5D3 according to DxO only has a 1 stop advantage over the K-5 at low-light, and the D800/D600 may also 'only' be 1.5 - 2 stops ahead of the K-5. That's certainly noticeable but not light years ahead of K-5/D7000 grade cameras.
Particularly since the K-5 does have a good ability to hold onto detail at high ISO, and achieve high sensitivies without (for example) the sort of disturbing banding that even some FF sensors suffer from when doing low light.