I will check out those links when I am off my tablet, but I'll just say that I have seen a great many shell shoes that look entirely appropriate with a suit, and never once thought the material alone would render them less appropriate than calf.
Design has vastly more to do with the level of formality than material - at least, as between shell and calf.
Don't shoot the messenger. I'm not the one who decided that shell is less formal than calf. I'm also not saying that your point isn't perfectly valid, because it is. I can see the logic behind why the heavier rolls that shell develops instead of creases, and the more hefty look that shell has (it almost looks chewy, like caramel, for lack of a better word) would make it less formal on average. However, I'm no stranger to seeing shell shoes that look like they could be worn to a black tie event as well. I'm just reporting the general opinion.