Well, I had to find out what all the fuss about the D800 was so a couple of weeks ago I went up to Warehouse Express and compared a D800e with my 5dII and Cambo DS with P45+ back.
This was a quick and dirty interior test so didn't reveal as much as shooting a landscape might. I used the 17-40 on the 5DII (as I said, quick and dirty), 14-24 and 24-70 on the D800e, and Schneider 24XL and 35XL on the Cambo.
Quick summary of results:
D800 has great dynamic range, pretty much up there with the P45+. Resolution, even with the D800e and 14-24 is noticeably less than P45+/Schneiders but still significantly higher than the 5DII, as you would expect. The 14-24 is a beautiful lens - big and heavy though.
Biggest surprise was just how inaccurate the colours of both the Canon and the D800 were - they simply didn't accurately reproduce what I saw. I'm looking back at the last 10 years of shooting with Canon digital gear, and slightly weeping at the thought of how the colours were never quite right, despite a lot of struggles in post. And even stitching to 100+MP using the 50 1.2L, the images aren't as crisp as the Cambo.
Here is a link to download full res JPEG12s of the 3 files.
http://dl.dropbox.com/u/10489236/D800 TEST.zip
Points to note:
My 24XL has a problem on the right hand side which Cambo should be sorting for me soon.
Note the colour of the floor - it's only right on the P45 file. Also, look at the 'blue' hanging signs, rendered as purplish on the Canikons.
All processing done with my regular settings in C1 - sharpening of 130/1.3/1 and I've just equalised exposure (imperfectly) between the 3 files.
Hope these are useful to some of you. I won't be getting a D800, simply because of the colours. Perhaps they could be improved with profiling but I'm waiting for Canon's (hoped for / expected) big MP whopper - if the colours are one step up from the D800. The convenience and high ISO performance of 35mm still has its place in my work.