Karen, a coat king is really easy to use and it doesnt hurt them at all. Alfie hates being brushed and combed but sits there quite happily when Im using the coat king on him.
Its best to use it on a well brushed out coat so theres no tangles for it to snag against. Then you just use little bushing motions in the direction of the coat growth. You will feel it resisting - thats the indication theres coat there to come out. Just work on a little area at a time and once it glides through effortlessly its time to move on to the next area. You will get tons out - quite frightening at first.
I use the coat king on the head, ears, back sides and legs. I do sometimes very gently use it on the chest. Its not recommended to use it on this area but I go very carefully and gently. There is also a story going around where someone supposedly cut their dogs neck to ribbons using it there, but to be honest I cant see how it happened as the angle of the blades dont allow it.
Anyway start of gently and you will soon get a feel for it. I started to use mine on Alfie at 7 months and only small areas of his coat were ready to "give". At ten months his legs are just about ready to strip