Got sent a free sample of one of these a while back, and it seemes a good quality product, a bit pricey though. Good firm retention of the pigtail connector, and the plug retention of the unit itself seemed very strong as well.
The one thing I did notice was, where the brass(?) conductors in the receptacle are formed up to make the contacts for the pigtail plug, there is a significant reduction in the size of the metal (a "cut" or "notch" to allow for the bend.) That area of metal looks too small to my eye to carry a load of say 15-20 amps continuously.
One of these days I plan to rig it up and load it down to see if any noticable heating at that point occurs.
Stupid should be painful.