I have them attached to the side of PAR can mounts for the PAR cans that I move around a lot - easy way to put them anywhere where there's DMX and power available. I have used them for 50W to 1000W lamps and they have worked flawlessly so far. They have also survived a few blown lamps. I have even used them to switch some random decorative LED lights or UV fluorescent lights on or off (without dimming).
The unit has a proper metal case and is built solid enough to survive more than a few bumps and drops. Overall build quality seems to be surprisingly good both outside and inside. All the terminals inside are properly secured, it has proper grounding, no loose screws, soldering is good. The switching element is a BTA416008 triac, which is rated for 40A and can handle 400A surge current for 20ms.
Only problems I saw where not enough thermal compound between the internal heat sink and the case (not really a problem in my case - the internal heat sink doesn't get that hot) and the inductor is only partially potted so you can hear some buzzing when the dimmer isn't fully on or off (I have one at home and it's a bit annoying but not really a problem on a big stage). Also the mains cable isn't very flexible
I replaced the 3 pin XLR sockets with 5 pin ones on my units. It was quite easy to do as there where extra solder pads for 5 pin sockets (but you have to remove 15 screws to get the PCB out).
The user interface (3 buttons and numeric LED display) is simple but intuitive enough to make the user manual useless.
If you need a cheap and reliable dimmer for incandescent lamps, without anything too fancy, this one will do fine if you don't mind a slight buzzing sound.