I appreciate what you guys are saying. It's been a while since I had my printing business so technology may have changed but neither we, or any other commercial printer I knew had any luck upsampling photos. The industry rule of thumb was DPI should be 1.5 - 2 times screen resolution on an offset press. So given an average screen resolution of 150 lines per inch (which is probably low by today's technology), we can get away with 225-300 dpi in a photo. This is why most printers want a 300 dpi photo. Yes the rules are made to be broken, but an A3 spread would see it down to about 175 dpi once you allow for bleeds and before any cropping occurs which is cutting it pretty fine by my book. These days, the use of stochastic screening may extend this a bit further but not by much.
Continuous tone Photo Prints are another matter, and certainly any of my 6mb pics print fine on 320x450 mm (oversize A3) on a calibrated graphics arts quality Colour CMYK laser output device. With one of these output devices around, I've never bothered with traditional enlargements.
So I guess it is me saying 6 mp is not good enough, 12 would have been enough but the market has moved past that plus I get a quality video camera for free! In any case, the deal is done, as I set my direction over 12 months ago when the D800's specs were unknown. To back out now means I don't have the right lenses for a DX.
I really am looking forward to getting my hands on this D800 and expect to have one in the first batch because I pre-ordered within 3 days of its release. I guess the good thing is that the $6-7k I've allocated to photo gear over the last 18 months ( including this purchase) has been fully funded, the lenses are to hand, I ordered the memory cards today based on the specs in the manual and Rod's camera fund has recovered enough to buy this body.
Some may think I'm wasting my money, but it is mine to waste and whilst I am not a pro, I've had an SLR since 1982, and do have a handle on the technical aspects of photography and the D800's resolution is playing into my hands with what I want to do in the future even if it exceeds my minimum requirements while addressing the weaknesses of a bottom of the range digital body that I have found frustrating trying to produce shots I've got paid for.