To be honest this is not my area of expertise. I followed the developments in MFD for a few years and have some very limited experience with MFD via demos by Calumet for my classes in Chicago and BetterLight Large Format scanning backs via a friend. Personally my decision to use a DSLR is largely a business vs. quality decision at this point. What can I afford to depreciate in a couple of years given the fact that I work in a small market in a declining economy, and which will give me the quality I need to satisfy my local and national clientele? The answer for me right now is a full frame 21mp DSLR (first a Canon 5D and now recently a 5DMII). The portability of a DSLR compare to a MF or LF digital camera is an issue too, because it translates to creativity and high production. Note! ALL my clients, including national magazines, design firms, international book publishers etc., have been happy with the my performance with a DSLR. Believe me, after almost 30 years of using a 4x5 view camera for architecture, no one is more surprised than me. But! I work very carefully, at each stage of the process trying to maximize file quality and mitigate the limitations of wide T/S lenses etc. Hence, I always work with a tripod, mirror lockup and cable release etc. much as I did with a view camera. It is about thoughtful and knowledgeable use of whatever technology to maximise image quality.
The new Sinar Archtec happens to be one of the few cameras designed by and for architectural photography.
I would love to test one but it is very unlikely that I will be purchasing one. See also Luminous Landscape. At around 40k+ with lenses and back (just a guess) compared to a 5DII at about 10K including lenses (and about 5K in upgrades every 2-3 years? In this market? With my clientele who are happy with my work on a DSLR? Not likely. I could really use a better 24 T/S and maybe the new canon is just what I need, but that is about it.