There has been a lot of grip questions lately on DGCR, heh.
Anyway, there are some advantages to learning multiple grips. Most people use more than one 1 or 2 grips during a round. I use pretty much three grips. I find they do everything I want.
Four finger power
Fork Stacked grip (KC grip you're discussing)
and fan grip
Putting still a fan just with the index under the rim not wrapped like around onto the inside rim.
Anyway, Going down the line they offer accuracy with a VERY SLIGHT decrease in distance till you reach the fan grip.
The Stacked fork grip is really one of the most well rounded grips and essentially to me makes up quite a few throws for me. But, anyway as mentioned the grips comfort is all relative. You could be performing a certain grip incorrectly which I was guilty of at times and got corrected on it.
The Stacked fork grip like mentioned does gain most of it's leverage by stacking the ring finger on the pinky finger like MrScoopa mentioned. The middle as said also isn't all THAT important, but can increase resistance if stacked also, or add stability if straightened across the flight plate. Your choice but does change the grip to a "birdy grip" essentaially. XD But, anyway. This grip is still rather powerful and shouldn't really hinder your ability to still get some good distance. KC does it quite well,
But, yeah again. You should just practice with it and try to ensure you're performing the grip correctly if it doesn't feel right, or you're really suffering distance, try to find some more pics and stuff. But, I also wouldn't recommend going to this grip for everything either. It's a great grip, but some grips are just as good in proper use..