Simon,

I don't think the issue is whether the Insteon device is silent or not. Rather, the issue is whether it is silent or not when operating in X10 emulation mode, as you would need it to operate in this mode to use the IR543 with it. I would guess that the answer is 'no' but I am only guessing. In other words, my guess is that the Insteon device is near silent when operating in Insteon mode but clicks when operating in X10 emulation mode. But, as I say, I am only guessing and the only way you will know for sure is to try it.