D800: what's the point?

That's not what he said in his OP. He gave samples of ISO12800 and then goes on to say that the K5 was better, when this is blatantly not the case. An A3 image from the D800 at ISO12800 will be better than an A3 image at ISO12800, not downsampling the D800 to match that of the K5 and then coming up with his flawed conclusion.

You do not compare pixels to pixels. People are not buying the D800 so they can print larger, they are buying it due to have ​versatlity and options​ and this means the ability to do large cropping, which means not requirung a DX camera for reach, the ability to shoot at high ISO with little penalty in noise and DR, plus the other advantages of excellent AF speed and accuracy etc.

Granted, at ISO100a D800 and D300 will be almost indistinguishable at A4, but it is when you get to higher ISO's that the differences become apparent. That is the point and partly why the D800 is such great cam.

The trouble is, the OP is taking ​one tiny flawed aspect​ of performance and devloping an overall conclusion on this one tiny flawed aspect.

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