I've never really needed that, or I don't understand the need for there to be a difference. I typically tile windows into each corner based on how large I need them. When I need more than 4, I'll manually place them.

What I do notice is the wasted space needed by the entire window border to accommodate rounded corners and how annoying it is to grab a window handle in e.g. Ubuntu w/ GNOME because you're clicking/touching where the corner would be (but isn't, because it's round).