Robland,
May be these info may help (all Japanese but you can see the figures etc):
http://fujifilm.jp/personal/filmcamera/mediumformat/gf670/feature.html
(see the lower part)
For finder mechanism:
http://www.nikkeibp.co.jp/article/column/20090312/138564/?P=3
I went to Fujifilm square in Roppongi Tokyo to actually see and touch the demo GF670 about two month ago.
The finder is the one of the high point of GF670.
Without any question, best of any folder (of course) and better than Mamiya 7II I think.
The shutter speed indication in the finder is very clear, have very good eye relief (no problem with eye glasses).
Magnification is X0.7, Coverage is 88% @ 3 meter, Effective baseline 25.9mm
I dont think that there is any indication of aperture in the viewfinder.
Metering is center weighted but SPD is not built inside the finder optics.
The parallax compensation is done NOT by moving the entire bright frame but moving the two sides of the frame, which results the area of the frame vary by focusing.
If properly designed, this will gives you better framing accuracy.
Just note that if you plan to put this camera into your pocket, this camera is relatively big than you might think (dont think that it is even close to classic 6 x 9 folder for size, such as Bessa II
it has Gauss type lens and lot of other features that makes the camera large, and it did not slip into my vest pocket, while the my Bessa II do, but I think your pocket will be bigger than mine but check it out if you care).
Lens seems to be good, seems to have good contrast.
But it does not seems to completely beat the performance of the specialist lens of good old Bessa II (55 years old Apo-lanther 105mm F4.5) in every respect, such as distortion, since this lens has some mild barrel distortion but I think it should be no problem unless you are taking architectural photographs (well this camera have no camera movements anyway) or very demanding for low distortion.
In this respect, you should use Mamiya 7 lenses or RB K/L 127mm F3.5 lens.
Even cheep Nikkor AiAF 50mm F1.8D are much better in this respect.