I saw those corners used by GK and when I built my own cabinets, my first idea was to use those, too. But I found them to be unhandy to use.
first of all you have to route the edges, which I did not want to do. OK, you cannot blame the corners to be designed that way, but I wish they would make a version for un-routed edges, too.
Secondly, they just don't seem stable enough to me. Cannot help it.