No question the MFDB files are better than 35mm dig files, to me anyway. But, CMYK web press magazine printed, who cares. DS1, ds2, ds3, 5d, P45 whatever. 14 stops of DR is great but you are always limited to what, a three stop range of ink black and (crappy) paper white in a magazine? I looked at some images I shot with the P30 that were printed on a web press and, well, they could have been shot on 645 film, or maybe good scans of 35mm chromes. What MF offers, and is reproduced on a web press, is the look of MF, the look of the lenses and the larger sensor. That is what's important with an MFDB, to me. (Shoot a girl under hard, contrasty lights and retouch it. That's where you'll see a big difference in file quality). So, in short, I would take the cash and finance some editorials for Mixte or L'Official or French or Dazed etc., have a web site redesign and a party kicking it off at Lit/Fuse, Mars Bar, or 124 Rabbit Club or something. That will make you more money than a back.
Agreed, and seldom mentioned.
The real advantage for medium format, in my work, is the difference in "look" or the perspective of the lenses. The differences in resolution and color are not important to me -- most of my work is for print (magazines or advertising) and has plenty of post-production.
I routinely use my 1DsII and the H2/P30+ in the same shoots -- their strengths are in their differences. Different tools, different applications.
The Canon is great in a certain type of morning or late afternoon window light, or open shade. It is predictable and performs extremely well, handles well, and allows me to more more freely with the subject.
With the Phase, I feel more connected to the process of image-making, feeling the image in the viewfinder as I press the shutter. The file are more flexible in post, and I prefer the perspective of the longer medium format lenses. But I find myself focusing on the camera more than I would like -- the whole system is really heavy, and I have to pay more attention to the autofocus. If only the H body had an extra focus point to focus on faces in verticals...
In the studio, and most cases on location, the difference in quality is worth it. But, most of that advantage is only for me to see -- once printed, the only difference that anyone will notice is the difference in perspectives or "look" between medium format and 35mm.
Just as it's always been, film or digital.