Roger, with all due respect, I use my view camera for landscapes where I can take advantage of perspective control offered by tilts, swings, and shift. If I want to create a looming foreground, i will use a rear base tilt. If I want to put the viewer at eye level will tall Sequoia trees and negate convergence, i will tilt the bed and correct for parallel with the front and rear standards. You just don't have that sort of control with any other camera architecture. The biggest gain in quality is not so much due to the increase in film real estate, it is because you can optimize the plane of focus, thereby minimizing focus spread and requisite aperture for DOF. As such, you are not into diffraction limiting apertures. I think it's important to also keep in mind that 4x5 lenses are optimized for f/22, unlike 35mm and MF optics.
My smallest print size is 16x20 and I have compared my Mamiya 7 against my Arca Swiss using Rodenstock APO Sironar-S glass for these dimensions. When there are no gains to be had with re-orientation of the focus plane (i.e. lens and film in-parallel), there is only modest gain in sharpness in going 4x5, but the tonal range appears greater and there seems to be a greater overall sense of depth, an enhanced 3D rendering if you will. As soon as the optimal plane of focus is no longer parallel to both the lens and the film, then 4x5 leaves MF in the dust, and the difference becomes more obvious as the focus plane becomes increasingly obtuse from parallel.
And finally, I am not constrained to the roll of film I have in the camera. Using Readyloads or Quickloads, I can mix my film types for the scene at hand. Light is fading, no problem, out comes the Portra 400NC. Beautiful soft "glow" light within the latitude of chrome, out comes the Velvia 50. This, IMHO, is a huge advantage over MF.
Just my 2-cents from someone who shoots everyday with both systems.
~ Jeff
