Finally I was able to test the new 24-105L II (basic testing - I am not an expert in that area)
For the record: it was not a kit-lens but separate lens that comes in the original Canon box.
The production date is October 2016 (4603xxxx67xx)
MK II
I see some improvement in mid- and corner sharpness at 24mm (f4) over the original version
Vignetting at 24mm (f4) slightly worse than the original version
Distortion at 24mm (f4) same as original version
At 105mm (f4) the center sharpness is less than the original version
At 105mm (f4) the vignetting is worse than the original version
At 105mm (f4) the CA is pretty much the same
The Canon dealer was surprised as well about these results. It is possible that I got a bad copy. They just had one copy so I could not compare with another MKII. Delivery is still difficult.
Somehow I think that the first batch has a QA problem after reading on the internet about other comparisons.
I decided not to replace my orginal 24-105. I will wait a couple of months into 2017 and try again with newer batches.