Marc,
That's not what i'm seeing around here.
Not just "most fashion shooters" but all 'shooters' 'shooting' for magazines and books use 35 mm format based digital, without encountering problems.
Mind you, that's not to say that there are no problems. Just that what they can deliver meets acceptance standards almost all the time.
Now, what, or whom is to blame for that is another matter.
It appears, by the way, that your 45 'meg' are MP, not MB. I took it to mean MB. Not that it matters much.
I do know how fast file sizes grow when tinkering with images.
One 'work around' is to flatten layers once youre happy with what they do, and save the intermediate result as an intermediate-result file. That keeps the file size from growing, though your hard disk will fill up a bit faster.
Another thing is to first do the adjustments that make use of the 16 bit original, and then reduce the bit depth to the usual 8 bit p/c.
Unless you're in a big hurry, i think it works.
Certainly when you reduce not just the pixel count, but also the image size to what the end use needs as soon as possible.
Anyway, this is not offering a solution to Tobias' problem.
Tobias,
I don't know about that choice: the Contax is a 'dead' product (no longer made, so 'system support' only available in the form of repair service), the Mamiya has been promised to appear before. The first too late to consider, the latter still very much wait-and-see.