... I would think this matter could easily be put to rest if the same landscape were shot under identical lighting conditions with a 22 megapixel digital back and, say, a Nikon D3x, using the best glass of equivalent focal lengths on each camera. After all... it is often claimed that even the 22 mp digital backs will clearly beat the best of the 35mm offerings. Shoot the damned images at = iso, process in Capture One (or whatever the best software may be for the that given camera) and print them out at 24x36" on fine art paper.
The main problem with your proposal is that the best glossy prints have a dynamic range of 8 stops at best, and the DR of fine art paper is considerably less. To show the entire DR of the capture would require tone mapping during the rendering, and good rendering is art as well as science (see Karl Lang
: Rendering the Print: the Art of Photography). This brings up the raw developer and its settings as well as the skill of the photographer.
Shooting at the same ISO would not be advisable. At high ISO the D3x would blow away a P65+. I would suggest base ISO, since if DR is critical, one should optimize it, using a tripod if necessary. For landscapes most would use a tripod anyway.
You would likely want to normalize for print size as DXO does, but 24 by 36 inches is too much for a D3x, since the print resolution would only be 168 pixels/inch. Also, 3:2 is not the aspect ratio for most MFDBs, and you would have to crop the image.The difference in resolution with a P65+ would be obvious. 22 MP is not state of the art for MFDB. You would be comparing old vs new technology if you compared a 22 MP back with a D3x.
Then you would have to make certain that the photographed scenes are identical and that the exposure was optimum with the sensor at saturation so that the full DR of the camera is used. You can't rely on camera histograms or histograms on the raw converter.
As Michael showed with his megapixel shootout, controlling all the variables and reaching subjective conclusions was difficult even for those highly skilled and knowledgeable photographers. Finally, as Michael pointed out, regardless of the test procedures, there will be nit pickers.
Nonetheless, the test you proposed would be interesting. Other things being equal, a larger sensor would likely come out on top.