Hi there, I think, if I remember right, WES runs under AQHA rules except for the riding 2yr olds part... and so you can use most Mylers in competition, as long as you have curb straps on bits with "hooks" and don't use the hooks in snaffle classes as that makes the bit a curb bit... if that makes sense. If I managed to confuse you even more, then go on
www.aqha.com and look in the rule book, it's all online and you can check english and western rules for all tack.
I showed my filly in a Myler snaffles and ported bits with a barrel with no problem.
Have fun!