Old thread, but in case you are wondering...
I had an XPFM in my attic controlling a spot light. If I listened carefully, I could hear it click on/off. Something went bad in the unit within a couple weeks, so I had the seller replace it. When they did, I swapped it out for the dimmer module. I prefer the non-dimming modules since I don't want to dim my halogens, but my wife did notice the click initially and wasn't pleased.
On the other hand, the sound is very similar to the XPS3. I have one of those in the attic above our bedroom closet and one above the guest bedroom to control attic fans. Those were not high WAF upon installation. Now that they've been there for close to a year, there have not been any complaints even when asked.
I'd say that the click is noticeable when close by, but you will get used to it. In my case, the WAF did return very shortly after explaining why it was doing it and how much it would cost to avoid it (Insteon switches were 2-3x more expensive for each switch).