Ok,
I am NOT a phd in physics, but I work long enough in the imaging indusry to know that difraction takes its toll around f11, if we talk APS-C. Your samples show nothing to me, really. Well, apart from the obvious depth of focus change. Scientific reviews show that difraction starts to show at about f11 (see photozone for example). If they are good they also say that f11 is still perfectly usable...
And there is one more thing: I dont claim to be right in a strict sense, I said it in my first post here. I just wanted to share why I - and only me - dont like "this kind of lens" and thus I am not in the mood to defense my position, since I am not offensive
Your milage may vary and thats a good thing!
Cheers