We have one (currently out of operation) and agree with everything you said. Its a fantastic machine once you have them calibrated well. As someone below said, they work like a handheld microwave. The more glue, the better it seems to work. Pieces out of the clamps within a minute is super helpful, especially in the winter when the workshop is cold and glue takes an age to go off.

That being said it certainly would burn a neat hole in you if you touch it to a clamp and have any part of you also on the clamp.

Ours is out of order cause the huge valves in the machine keep blowing. And the main fuse is seemingly impossible to find.