Hello! I have been thinking about this since a while ago. The letter "K" is considered by many as a non-premium letter. Some even regard it a bad-letter when it comes to lll or llll domains. But if you think about it, K is a hard consonant and has an advantage when it comes to making a short domain pronounceable. The consonant "F" is softer but it outpowers "K" when it comes to acronym possibilities... Personally, I tend to think that a triple premium + K in a llll.com as a quad premium. I have come across a few domainers that think my way...and have met some that are reluctant to consider "K" as a premium letter. Your feedback on this would be much appreciated. Cheers!
Like I have said many times, it's not about K, but about finding someone who likes a domain which includes it, or have a good marketing plan to develop a website without being confused with the C version of a name.