Is there anything besides the number of pixels that differentiates Medium Format DSLRs and 35mm DSLRs?
Henry, it seems this topic was beaten to death in your previous thread. I don't know what more can be gained by talking further on the subject. I think you need to borrow a system for a day or a weekend and do your own comparisons on your own monitor and in your own prints. Most of your questions are somewhat subjective and can only be answered by doing your own testing.
Call Steve Moeckel at Schiller's in St. Louis. He should be able to get you a Phase One back and a Mamiya 645 II (maybe even the new Phase AFD III body) to evaluate. He might even be able to get you a Hasselblad system, tho I'm not sure on this. He was able to get me a Phase/Mamiya system to use for a long weekend, and I'm sure he could do the same for you.
I personally feel the major difference between the latest 14-bit DSLRs and a MFDB is the number of MP, and the lack of an AA filter (that difference should not be underestimated, however - it's not something that you can easily make up for by stitching, as you suggested in your previous thread). However, I only use my MFDB for natural light landscapes. I don't know if my observations hold in other circumstances (for example, I might have a totally different opinion if I shot in a studio). Also, since I'm shooting with Mamiya lenses, which aren't the sharpest, I might be doing the back a disservice. I'm sure there's better glass you can put in front of a MFDB, for instance, that would yield sharper images and better micro-contrast, and might therefore reveal even greater benefits over DSLRs.
Do yourself a favor and get your hands on a demo system from Steve.