I got the impression the original poster would not spend more than 14000$US or so. Si I guess the IQ180 is not an option.
More affordable backs often come with a crop factor. So, the potential buyer must consider his/her needs regarding wide angles.
MF Digital is said to have many magical properties, like CCDs offering better color than CMOS. In real life life both CCDs and CMOS are monochrome devices, with color added by the CGA (Color Grid Array) and the software. It is well possible that certain vendors have better CGAs. It is conceivable that some CGAs would put priority on good high ISO performance and others on good color separation. On the other hand, real world imaging experts like Jeff Schewe and Michael Reichmann say that you can achieve essentially any color rendition in the raw converter. In his latest book Jeff Schewe illustrates that a properly processed image from an IPhone 4S is virtually indistinguishable from a P65+ at small print sizes.
Now, I don't think there is anything magical with MF. A larger sensor has always advantages, we have seen this with film and we see this with digital. A larger sensor can collect more photons. A larger sensor is also much less demanding of a lens. On the other hand, larger formats need to be stopped down more.This was so in the film times and it is so now.
An excellent study was done by Lars Kjellberg in film days: http://www.photodo.com/topic_138.html
I also would say that Nikon has shaken up the photo world a little with the D800/D800E. That camera has a lot to offer:
- Very high resolution
- Perfect focusing when using live view
- Best DR at the pixel level of any camera on earth
- Access to a wide variety of excellent lenses from Nikon and Zeiss
- Option to use Leica R lenses
These factor make the D800/D800E into an excellent picture maker. According to at least one test by Lloyd Chambers the D800 actually outperforms the Leica S2.
For the price of a digital back you can probably build a whole system of a Nikon D800E and a few of Zeiss lenses. So, quality wise the Nikon option should be concerned.
There is little doubt that high end backs with high end optics outperform the D800/D800E when optimally used.
Stitching is an alternative in many cases. Stitching is easy. Stitching can expand resolution capability, but it is not always possible. Stitching may also help expanding angle of view. This of course applies to both MF and lesser DSLRs.
Whatever equipment is used, it is just a tool. The tool needs to work for the application. A nice tool is nice to work with. It may be important that the user feels satisfaction with his/her tools.
That's so funny coming from you, Bernard! "stitch, stitch, stitch.... "