Here is the problem:
You get exactly what you pay for. If you use a cheap slide dimmer, chances are that you will get nothing more than a resistor with a knob on it. The device will be nothing more than a heater that absorbs unwanted power to the lights. (Hence the big cooling fins on these types of Dimmers)
It is better to go with a high frequency type dimmer, which switches power rather than absorbing it. (These generally have much less metal on them) The still get warm but not smoking hot.
Here is another issue:
Ganging: If you get stuck having to use wall-box Dimmers on a job with more than a few devices per room, get ready to take over a nice big part of the wall. The ideal situation would be 1 Dimmer per Box … period. Otherwise you could end up going back again and again, replacing Dimmers under Warranty ( Yours ). Depending on the Spec that could prove expensive for you. Too much heat will take these things out real fast.
Forget about anything more than 2 gang boxes with dimmers in them…
The way I feel, Wall Box dimmers are nothing more than an afterthought to a switch. Amazingly, many Architects still put them on the plan. If you have a lot of Dimmers on a new Job, you will be better off using some kind of Architectural Dimming System. (They do not cost as much as most people assume) We call them energy management systems for people that are afraid of the word Dimming System or those that are technology shy.
I am not even going to mention that there are at least 3 types of Dimmers that you must use, depending on the load connected.
Btw. I wonder if a new replacement dimmer every couple of months would be more bothersome to the customer, or to Lutron?