Are Kaby Lake CPU’s worth it? It really depends. As most of you know, the Kaby Kake line of processors are based on the same 14nm process, still on the same LGA 1151 socket as the previous Sky Lake processors. This means that these processors have the same performance as the Sky Lake architecture, except that they have higher clock speed.
The reason why the Kaby Lake CPU only have slightly better performance is because of INTEL’s lack of competition. Now however I think that RYZEN the new AMD cpus are going to be very competitive against INTEL’s CPUs.
If you are not interested in the RYZEN line of chips, and you only want INTEL, then I recommend the following. If you have a Haswell chip or later, then its really not worth getting the Kaby Lake line of chips, since the performance is not as much.