i use a boom vang 3-1,on a run, i uncleat it before going up wind, it holds the leach tight. but on a 2 up boat i have seen a single rope used (kicking strap) to stop the boom going to high through a jibe. other than that it is not really needed.
brooken dimond wire was from rushing and not crimping the wire right, i should have used 3mm wire, it was only 2mm.