In terms of "softness" I had a Mark II for almost three years and now I have two Mark IIIs. The Mark III is very sharp. It is sharper than the Mark II and the IQ in terms of color and ISO are superior. I can't imagine the the 1Dx having a "softness" issue if the Mark IIIs images are extremely sharp.
Yeah? Could you post a couple of raw's, say of a barcode and small text, I can compare to mine with? because mine is def softer than my 5d2. Serioulsy different.
that would really help. at full resolution please, a RAW file would be perfect if possible