I've had embarrassing MS-DOS moments in the past where I was typing out something like a recursive-delete on a path. If you accidentally hit RETURN instead of a backslash then you can do things like blow away entire parent directories unintentionally. This didn't exactly improve my already-critical view of PCs. :)
I have never seen a PC keyboard with the backslash anywhere other than in the bottom LEFT corner next to your left smallest/pinky finger with one exception: in Germany and France, they keyboards sometimes have backslash on the top line numerical keys.
I .. switch all my keyboard to the US layout because I feel that I kill my fingers otherwise to reach {[]}| and \
On the other hand, the computers at Bell Labs had an arrow key, which is why R (which is based on S) uses '<-' for assignment, as the two-character combination was enabled for compatibility reasons.
And on a related note, I can't imagine how people use Vim without rebinding ESC to Caps_Lock. Given that ESC used to be where TAB currently is (and the latter is too useful to be removed), I don't really see a point in keeping the obsolescent Caps_Lock, especially when it's so irritating to keep moving the hand to the furthest corner of the keyboard.
I have also dealt with crappy tiny keyboards that don't even have any keys beyond the standard chunk (So no function keys, 10-key, or arrows / browsing control)
My favorite keyboard happens to be the Apple Extended Keyboard II, but I can't use one these days because its caps key would physically toggle between on and off states (like a typewriter caps key) which means it does not make a very good candidate for remapping.