Hi Robert,
In addition to re-iterating the "use your eyes" advice given in the messages above, I would also recommend you spend a little time reading up on the meaning of the various types of lens test results that you're referring to. The best place to start is Photodo.com, which gives a decent explanation of the type of testing - MTF testing - which they perform. It's really not massively difficult to understand, and a half hour's reading will put you in a much better position to make informed judgements.
The medfmt site's analysis of Contax 645 glass is based entirely upon old-style resolution tests, quoting performance in terms of lines pairs resolved. This kind of test sets out to determine the finest detail that can be distinguished at a given aperture. A lens which performs well in this test may not actually provide good contrast for slightly larger image details, meaning that it will not look as punchy as another lens which is a worse performer in an outright resolution test.
I would definitely recommend Photodo.com as one of the more reliable available sources of lens sharpness data. Many people don't look beyond the summary scores, but it's well worth learning how to read the whole report as it contains much useful information. For ex&le, look at the figures for the 80mm f/2 Planar. This lens has an overall rating of 3.8, which would tend to indicate that it's pretty good. However, the weighted MTF figures for each aperture are revealing: f/2 0.56, f/2.8 0.67, f/4 0.76, f/8 0.82. In broad terms, these figures show how sharp the lens is at each aperture. A (physically impossible) perfect lens would record 1.0 everywhere. The 0.56 figure at f/2 indicates that the lens is indeed fairly soft wide open. This is exactly the same situation that exists with the 85mm f/1.4 Planar for Contax 35mm cameras -- the lens behaves almost like a soft-focus lens wide open, such is its softness. The situation changes dramatically as soon as you stop down a bit, though. You see a big jump in contrast even at f/2.8, but by the time you are at f/4 you're definitely "cooking on gas". These are MF lenses, so shooting at f/4 is going to be dicey in terms of depth of field, never mind f/2, therefore in practical terms this lens is going to be a stellar performer. If you want to shoot at f/2 for creative effect you have the option -- something the other manufacturers are unable to offer.
The second set of weighted MTF figures show how much contrast the lens preserves when it images test patterns at three different spacings, chosen to produce frequencies of 10, 20 and 40 line pairs per millimeter at the film plane. The figure for the coarse pattern will always be better than the lower ones, for reasons which are hopefully obvious. Counter-intuitively, it is the ability of a lens to provide good contrast for relatively large features which gives the much of what we perceive as punch and sharpness in the image. Therefore the first thing you should look for is a decent showing in the 10lpmm figure, and the 80/2 scores 0.89 which is a very good result. The 0.75 score at 20lpmm is also good and the final figure of 0.51 at 40lpmm is passable. (Interestingly, the figures are almost identical to those for the 80/2.8 Planar for Hasselblad.)
It's also worth mentioning (since the author of the medfmt article seemed unaware of it) that although it is indeed true that the 645 lenses are made under license by Kyocera, the same applies to the Contax/Yashica 35mm format lenses and these are rightly regarded as among the worlds finest optics. In the end the designs are all prepared by Zeiss, and it seems that Japanese standards of assembly and test are well up there with the best that German firms can achieve.
As a final comment regarding the lenses, I would fully agree that background blur (bokeh) is a huge factor in lens choice, and this is where Mamiya and others cannot compete with the best German designs. I speak from experience as a (very satisfied) Mamiya 6 shooter. Much as I love that camera, there is no doubt that my 35mm Zeiss glass has the edge when it comes to smoothing out the background, which can make all the difference to portraits, especially.
As regards the body and the rest of the system, I would only suggest that you go along to a store and try handling one for yourself. I picked one up in an idle moment recently, and was absolutely gobsmacked by the rightness of the handling. The Canon-style ability to override the AF just by turning the ring is a boon, and ring itself feels like a proper manual focus lens. I wasn't aware of the small viewfinder coverage, but that is a bit of a shame I guess. The viewfinder itself was clear and usable thanks to the fast glass. I didn't feel the AF was particularly slow or unstable despite the poor interior light in the shop. If I had the money for a 645 SLR system right now, I think the Contax would be a very strong contender. I would certainly select it in preference to the H1 at this stage.
HTH
-= mike =-
