Why hot wire? Only because I don't want to walk to the breaker panel in the garage "every time." By "every time," I refer to a current trouble-shooting matter in which an old, mechanically failed WS12A-type switch was replaced with a new WS12A that worked for two days; then quit. I have another new WS12A and will wire it with the power off...as I usually do.
BTW, the label on the X-10 WS12A module says to wire Line-to-Black and Load-to-Blue but the instruction sheet in the package says just the opposite. X-10 customer support said to follow the directions on the module; not on the instruction sheet.