I agree to a degree but I feel like kc being able to proc onto itself will have the same impact as rampage spec since rampage have easy prcoing requirements (just three kills), but had to upkeep. Swashbuckler can proc easily by a melee but have 5 stages to get to its full potential, and multikill clip requires 3 kills before reloading which is relatively harder than kc, therefore, getting the most in return. I would say that rampage spec also eliminates its weakness by making maintain the buff much easier and getting more in return for the same amount of work. With this kc mod I feel like it would not replace rampage because how easy it is to proc it, and the reload inconvenience of kc (although reload perks negates the inconvenience), also perks such as subsistence won't work with kc making rampage and swash the only damage perks viable with subsistence.