The 15'' K dark thin crash is an exceptional cymbal in certain situations, but not in most. K's are often played in Jazz, and we had one of these in my high school jazz band. It served well, but to be honest I usually opted for larger dark cymbals when crashing. It was difficult to get the needed power out of this cymbal. It felt so soft to hit the response was sort of delayed. The bell was also very weak, but this can be attributed to its size. It sounded beautiful by itself, just not so much in context.
It is a little small for a crash, especially one that is dark and thin. It is difficult to get loud, lasting sounds out of these cymbals when striking sharply with a stick. Recording with this is especially bad, because it is so dark and weak that all other noises tend to overpower it. This is true of many dark cymbals to some degree when recording (depending on how nice the studio is), but the small size and lack of thickness really highlight these qualities in the 15'' K.
One thing it was really great for was concert band, or any other subtle playing with mallets. This is one of the best concert band cymbals I have heard (for reasonable small ensembles) because of its soft, dark nature. The same things that made me dislike it in jazz or rock made me love it in concert band. The sound built up smoothly and evenly when rolling in a crescendo, and the sound was perfect for the band.
Clearly this cymbal has its strong points and its weaknesses. Everyone has their own preferences, but it was not for me. For its expensive price, it was not nearly versatile enough. While great in concert band, and by itself or exceptionally quiet sessions, it lacked the proper qualities for normal playing or studio recording. There are so many good cymbals for this price, I would probably not suggest this one except for specific circumstances.