I once heard a report on a new study that revealed that walnuts have incredible health benefits. It all sounded great and I was about to go out and buy some until I realized that this 'scientific' study was paid for by the walnut growers association. I'm not saying these tests are invalid, and as someone who does test a lot, I know how hard it is to satisfy the internet forum community. It's always good to know if there are any vested interests in tests, and who the sponsors are, as well as what wasn't tested and why. I don't know, maybe the lenses were chosen totally randomly, but why take new mamiya lenses and compare them to ones from a rental house (presumably with unknown used condition)? I guess in the case of the pearl projector it would have been difficult to test stopped down - but as people have pointed out what does that prove unless you are planning to shoot wide open at infinity a lot? And if a camera system was developed with DAC as part of the design, is it a fair comparison to test without? What camera system in the future is not going to take advantage of DAC?
There are some fantastic mamiya lenses especially if you count the 7 and RZ series, and I don't think anyone would argue that the lenses for the 645 are not sharp. But would anyone expect less? The parts of the optics that need to be tested and compared are the way the lens draws, near far focus optimization, distortion, build quality and operation. I think most of the criticism of the mamiya glass stem from the appearance or cheap feel of the 645 lenses, or its carryover from the body (which unlike the lenses does deserve criticism).