I've been using one on Tobes for a year now. I don't use it much and move it quite gently when I do and it removes loads of fluff. If it was uncomfortable for him, he would soon let me know. (no way would I use it like the lady in the vid).
Overall, I'm really pleased with the results but in direct sunlight you can see where the coat king appears to have cut the coat but as we don't get much sun, it's not really a problem.
It's the best way, for me, of achieving a show look without hand stripping.