I'm a happy new owner of a good old Aptus 75 and a tech camera, and curious engineer as I am I've made some testing. I don't have particular high expectations of MF sensors, it was more the camera and lenses I wanted so I have no prestige in the results.
The resolution aspect is obvious, 33 megapixels is 33 megapixels. Not having the AA filter has effect too (good and bad). I've also looked at noise performance and it is perfectly ok, better than my Canon 5D mark 2 of course, but worse than an APS-C Nikon D7000 in the shadows, and on par or a little better than it in brighter areas (when the lower photon shot noise of the aptus comes into play), all expected from measurement data others have provided.
What I'm still curious about is the "hyper-reality" aspect of MF that some claim to see, more or less vague description of properties that makes the MF picture inherently better than smaller formats. Better color rendition, better tonal range in midtones, more "3D look" (DOF/bokeh rendering from the lenses rather than the sensor I presume?) is things I often hear and all of it may be true but I have never been able to find any pictures to support these claims. Well, until I readhttp://www.luminous-landscape.com/understanding-series/everything_matters__it_is_all_about_the_small_details.shtml
under the "hyper-reality" and "first myth" section. Doesn't look like a well-controlled test though, you don't need to blow out highlights like that, that's poor technique. Maybe he is comparing in-camera JPEG with MF raw, I don't know.
So I kind of still wonder if these differences are real or if they fall flat when actually compared with the best DSLRs (D800/D800E on top today I guess), as I would say the more easily verifiable DR claim does.
Is there any examples out there to show us MF dummies, preferably seriously made side-by-side shots by someone who knows how to use both systems. Or maybe this is just a too controversial subject? Or even beating a dead horse, it feels like this small format vs MF is discussed in hundreds of threads, but the picture comparisons is extremely rare still...