Upload & Sell: Off
I will be selling the 24-70 f4 is. In all fairness, it is certainly better than 24-105 in the corners, even at f11, and has less distortion. It also has the macro which is nice. however, I dont see myself ever travelling with that lens alone for landscape or any other reason. the 16-35f4 covers the wide range, and 24-105 is quite good from 35 on. at least a good copy of it.
Also, I did have a 24-105 which I purchased used as a part of 5d package. I got my current lens with intent to sell it as part of package, but it was a fair bit better than the old one. So I fully believe many people that complain about the lens. Bad copies are out there.
As for tamron, I am on my 6th copy. Crazy. this one is a golden copy, sent to me by tamron, when they had my camera and tested it with it. all the other ones had combination of decentering and focus issues.