The orange and black (above) work so much better in my opinion. The red just isn't as cool. The red isn't horrible, just not as good. The black background and the white lettering also ad some visual balance and unifies the layout. In many of the older stickers, WARNING! was forced into a rectangular black box (like the !DANGER below). Visually, i don't like this newer, larger WARNING!, but I can understand the reason for changing it.
The sticker below fails to hold my attention to a point where I finally read all the text. The strength of the crane warning sticker is the all-caps subtitle below the cool image that reads THIS CRANE IS NOT INSULATED.