I did one meter test. And this is another, maybe better one. Again, this is not scientific...
Setting, Kodak gray card, 3 feet away, with even filtered natural lighting. All cameras are set to spot metering (be it 1, 5 or 7 degrees). Aperture set to F8 (or as notes). Tests:
Minolta M spot meter: F 5.6/9, or very close to F8, 1 sec.
Nikon F100: F8, 1 sec.
Nikon D200: F8, 1.3 sec
Bronica SQ-A AE III: F8, 1 sec
Bronica SQ-Ai AE III: F8, 1 sec to 1.5 sec (1.5 sec is the next level above 1 sec)
Bronica ETR-Si AE III: F8, 1 sec to 1.5 sec.
Bronica GS-1 AE (average metering): 1 sec.
In general, the results have been consistent. Of course, this is not actual metering situation and there are many other things to consider.