Editors are demanding megapixels?? Really? That's nonsense. Editors dont say "your camera better have X amount of megapixels or no deal!" who told you that? One of the biggest reasons why a bigger pro wouldn't use the 5D2 over say a 1Ds3 is durability and such. They really but their cameras through hell and shoot a ton. And a big part of the time the gear is rented. They have big ol rental house stickers all over the lenses, camera bodies, computers and such. There's a tech and number of assistants running the tethering if they're tethering and running lenses or camera bodies with specific lenses and handing them to the photographer. And some landscape photographers I've shot with use Large format and medium format Phase One backs. javierherreraphotography.com judge all you want, doesn't take food out of MY mouth. AND when did I ever judge your work?
Who told me that? More than one magazine editor back in 2008 - it was 20MP or no deal. Either native digital files, or high-quality scans. Also, every second gallery, when you start mentioning digital prints of landscape shots. Usually, it goes something along the lines of, 'OK, we want to blow this up to 100 inches wide to display on this wall. Can your file handle that?'
And don't try to lecture me on landscape photography unless you're also one yourself. Landscape photographers sometimes use MF digital and LF film, but only in benign conditions, and generally when they don't have to carry it far. There's a reason many of Nat Geo's landscapes are shot using full-frame digital (similar IQ to MF film), usually the 5D2 or 1Ds3 - a flimsy MF or LF body is a liability if you're trying to shoot in Antarctica, or if it's too big and heavy to reasonably carry to Everest's North Col, or into the Congolese jungle. MF film panoramic bodies were very different from the current, flimsy and cumbersome field camera setups you need in order to use MF digital backs (since no MF DSLR has lenses which are wide enough). X-Pans, 612 and 617 lenses and bodies were relatively compact and robust. Stitched DSLR shots give similar IQ in similarly robust bodies. Digital MF backs in field cameras have similar IQ, and a similar size and flimsiness, to large-format film field cameras. Which makes them very special-purpose items. If one were available in a robust body (say, a digital x-pan with a 24x72mm sensor) I'd probably own two of them already.
Obviously durability is a big plus for the 1Ds3. It's also a big plus for the D800.