Naturally, this "switch" could only be used when text, or another item, has been selected either through use of the mouse or a keyboard shortcut subjective to your operating system (e.g. shift + left/right). Given that one of the two aforementioned conditions must be met before the switch's ability is enabled, it would be slower than either the traditional CTRL+C and CTRL+V combo, like previously mentioned, as one hand would have to change from the typing position over to the left hand side of the keyboard. Even if the switch was placed on the mouse it would only be effective if the item was selected by the mouse, which may well be the case sometimes, but in cases where the user rarely uses the mouse (e.g. word processing), it wouldn't be nearly as efficient.