I had a chat with
The problem is that if someone, who trained himself to use a customized keyboard layout, needs to temporarily work with another computer, which does not already have his layout – he needs to mentally switch to the standard keyboard layout. Very difficult and highly error-prone.
A solution to the problem would be for people to carry around personalized keyboards. When they need to work on another PC, they plug their keyboard into it and start typing. This calls for standards, and for hardware+software design, which allows keyboards to be plugged and unplugged at any time.
A first step could be for a standard keyboard to provide an USB socket, which allows an user to plug in his own USB keyboard. When a customized keyboard (which, by the way, could be also a chord keyboard for very rapid text entry) is plugged in, the standard keyboard will just pass on the keycodes from the user’s customized keyboard to the PC.
Another problem, which the proposed USB socket in standard keyboards would solve, is that people, who need to use special keyboards due to motor disabilities, are no longer confined to the single PC provided to them at work with suitable keyboard.