The only reason to shoot MFD, in my very humble opinion, is for the look of the larger chip and the availability of MF lenses. Resolution doesn't really matter unless you are selling giant prints (or want to be secure in the knowledge that your sunset picture can be printed at 40x60). Is this worth 8 large? The price of a D3x or M9? Maybe.
I am certainly not an MFDB fanboy, but this back produces the best file of any back, maybe the Leaf 75 is a little better. I think its a better file than the D3x, not by much, but there is a difference. What an MF back gives you over the Nikon is access to different lenses with a bigger chip, that gives you a different rendering. That's it. Is it worth the hassle of shooting a back? The limited iso, the strange screens, the need to tether, all that light you need? Maybe, maybe not. Its a tool in the tool box, and at $8k, certainly not that expensive. Not cheap, either, but not bad.
I have a 54s that I use only occassionaly on an RZ and a Sinar P. I mainly shoot motion now, but when I shoot stills, sometimes the Aptus comes out, sometimes I rent a D3x/1ds3, sometimes I shoot my M8, and sometimes I shoot film. It just depends on the project. So its not an either/or choice, in my opinion. If your work demands the look of MF, the rendering of the lenses, on a regular basis, buy one. If it doesn't, don't. Just rent if you need it. If you've been getting by with 1.5 crop sensors, I doubt your work requires the rendering from a big chip. A D3x will probably get much more use.
Even if the back plus camera, plus lens is 8k, why should I take that over a Nikon d3x or much more importantly, a sony a850, or canon 5d2. I have devoured the information on these boards for a while, but I can find a compelling reason aside from these things:
Sync Speed (you get a camera capable of leaf shutter lenses)
Lower Min Iso
Bigger Viewfinder
No AA Filter
Subjective Other Benefits:
You look more professional with a bigger camera
"better" lenses (though given the availability of zeiss glass on all of those platforms i would disagree)
"better" color
Is it really worth paying 8k or 10k for a digi back plus phase cam and 80mm lens for those benefits? I really don't think so. I have been waiting and watching eagerly to see what the market will produce before I take my next serious step up in digital, having been shooting with the d2x and the d300 since they came out. I don't even have that much lens investiture because I only buy what I use a LOT, so it certainly wouldn't bother me to move to a different system.
My point is that I just cannot see the cost benefit analysis working right for this. I think you may pull in a bunch of dentists who had not considered MF Digital because of the costs, but I don't think I know working pros who would drop 8 or 10 or 11 grand on a back that only provides those benefits.
Perhaps I am crazy.
