To clear things up, I intended to address following mfd user demographics (my segmentation, feel free to change it or give inputs, just my gut feeling of what users there are):
1. Never. I don't care about paying 10x as much for 10% more quality.
These are people that want only the best that technology can offer and don't care if means spending a lot more than a more common professional solution such as a 35mm digital system. Real-world efficacy as a tool is not the prime motivator, and money is no object or of subordinated importance here, no judgement intended. Classic example would be the the wealthy enthusiast who always buys the best of the best in all what he does or just quality-oriented consumers that appreciate the best technology or that want something not everyone has.
2. C'mon, D800 will never match DoF, dynamic range and microcontrast of my Phase One!
The decision to shoot MFD is based on clear-cut perceived/felt advantages and not a per se decision to shoot only the best. This user tried extensively different camera systems went to a dealer etc. and sees the special something only mfd files have.
3. I'm into tech cams.Won't give up Rodesntocks & stitching, even if that luxury costs me 40k more!
Tech cams afford unmatched quality in wide-angle photography, enable stitching for extreme resolutions and make up for a view-camera-like experience in the field. Especially high-end architectural photography benefits from tech-cam photography and there's no subsitute for this in 35mm except the TS lenses. Basically same as 2. but with a focus on the special tech cam experience that just doesn't exist in 35mm.
4. Damn. I just sold off my Canon/Nikon gear to get into MFD!
Anyone moving up to mfd because they want either more resolution or that special something of mfd and that just sold all their beloved CaNikon gear and kind of regrets not having the possibility to shoot all that well-known glass on that new sexy Nikon. It was hard selling that 70-200 2.8 IS that made so many beautiful portraits, wonder how that one would fare in 36 MPX.
5. If that Zeiss/Leica glass on the D800E performs as I think it should ... EBAY here I come!
The practical guys. Those who know that only the end result counts and not the highlight recovery slider in Capture One. In the end, printing that MFD file out in normal sizes (35mm digital such as a Leica M9 can go 40 inch easily) on that Epson or downrezzing that wedding portrait for the client's dvd is a great equaliser. Basically, if the D800E satisfies the client, no need for fancy mfd, and all the small headaches it can entail such as expensive upgrade paths (massive devaluation) or gear insurance. Great handling, speed, cheap costs of entry for great end results. Live view. This user doesn't compromise on quality, that's why he got into medium format digital in the first place. But it was a long road and money is an issue. They know that great glass is great glass and a Leica 100 Elmarit-R with that profoto Acute pack makes a new Nikon sing and interesting all over again and all of a sudden the idea of selling off that Hassy before Photokina arrives and especially before the newly announced systems devalue the secondary market price of one's gear by incredible amounts seems a lot more tempting. And hey, 4fps is great in comparison to 1fps. Love that snappyness in conjunction with the peace of mind that even being robbed of one's gear at the next outdoor shooting isn't going to cost one's arm and leng.
6. I just preordered a D800E. Hell it's cheaper than that MFD lens I'm longing for!
As a matter of fact the D800E costs less than say a new leaf shutter lens on a Phase. That's chump change for those accustomed to medium format prices. Even upgrading a P65+ to finally get a decent screen (and a little more bells and whistles I know) to an IQ160 ... costs multiple times as much as that Nikon. So for those people the saying holds true: horses for courses or outright: double system, here I come! because actually the D800 is so cheap that it's not a question of alternative systems but more of fancy. In the end, what Nikon has done here IS something special. Now we have the resolution-champ of the 35mm camp not coming in at 10k like it was the case in the past (D3x and 1 Ds MKIII) but at a mere 3k. That is the traditional price point of enthusiast camera gear or midrange pro-cams such as the venerable D700, or the 5D lineage from Canon. By introducing 36 MPX at 3k, Nikon is coming in so cheap that it's also tempting and so easy to hit that pre-order button on Amazon. For those accustomed to the PhaMiyaBlad price list this price is really easy. Leica users can smile even more because their lenses cost more than twice that little nikon camera or for one Leica-S lens they can get a whole new system with lenses.