I don't see how file size is an issue here. You can get TB drives relatively cheap now and they will only continue to drop in price.
It is unless you are privately wealthy/with deep pockets/or pulling in tons of money. It's like a chain of dominoes, f all of a sudden you triple the file size, its not just about after the shoot storage, you then have to triple the amount of CF cards you have. Then there's workflow, with larger sized files comes the need for greater processor power. I do a lot of HDR and panoramic stitching, and my PC already has some issues stitching panoramic (granted, that's when I'm trying to stitch 20+ shots). Either way, add it all up, ok, so now i need new harddrives, CF cards, and potentially a new computer to process it...$100 here, $300 there, $1500+ there, it adds up. I think one of the biggest flaws that I have heard about the D800 is that there's only 1 Raw option, and it puts out a gigantic file (around 75Mb per image?

) - or 7360 x 4912 - how many wedding customers or portrait customers are looking for prints that are literally bigger than the walls of the houses they live in?
I can see a camera like the D800 being an amazing thing to have if i was privately wealthy. It would be the thing I'd use to shoot stuff for fine art, to print giant and sell for a giant price tag. But, for most use (portraits, events, weddings), the file size of that beast would make it be the secondary cam, the one you pull out for the the ceremony, for the kiss and the formal portraits, then put the beast away and use something with a more manageble file size (i mean really, people will want prints in an album from a reception, but with the exception of the cake and dances, would they really want reception shots printed larger than 8x12? Note, as I say that, to warrent 7360 x 4912 resolution, you have to be working for someone that not only wants prints larger than 40x60, but people that will cut it apart with a microscope to tell the difference.
I think, the 5dx has the option to create sRaw, mRaw and RAW, then that right there makes it the better camera.
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