I think it’s more a case of marketing and snobbery. I really doubt that one person in a million could identify the size of sensor used to take a picture from the image.
Are you sure that you aren't in denial Andrew? There is a measurable difference in noise performance between a 4/3 sensor and a full frame sensor of the same resolution. A bigger pixel will generally display less noise. I agree that at "normal" ISO settings noise may not be noticeable but pushed a few stops it will be visible. I am not suggesting that 4/3 is obsolete, or even obsolescent, simply pointing out that there are physical limitations involved.
I think most people would obviously tell the difference at the sort of ISO levels I have to use for a lot of my conference stuff - don't often have the luxury of working as low as 6400, often much higher. I agree completely that most of the time you have to pixel peep unless you're going very large.
I'm sure. I used full frame pro Canon kit until a few months ago and at the same time used middle of the road M43 equipment. I couldn't see a difference so I sold the Canon outfit and extended the M43 outfit. As I'm always pointing out: everone's mileage varies and what I want from a picture will be different from what you want. But I stand by the claim that only a tiny minority will be able to tell the difference in practice.
Even without the cost consideration, there is also the size and weight to consider before writing off half-frame (APS-C) DSLRs, and the size and weight of the lenses too of course. I use a 16 megapixel half-frame DSLR and am very happy with the 40 x 50 and 50 x 75 cm prints I have had done from its images. There an be a problem if you want a large print from a severely cropped image, but even this is possible if a decent lens was used (I have a 40 x 50 cm portrait format print taken from a landscape format shot, so only about 9 megapixels used. But it was taken with a Sigma 10-20 at 10 mm and F 9.5 and the file for printing was processed from the RAW file. When working with the smaller sensor and 'only' 16 megapixels, time spent in carefully framing the shot to minimise cropping enables the best possible prints later.
ePh*t*zine have put up some sample pics from the S1R, should anyone be interested. Shot on a pre-production model (and only up to ISO6400), but that shouldn't make much difference, should it?
And now the S1H details are out. The movie oriented model, with a built in fan to keep it cool! Available from 19th September, £3,599.99.