I have a HKC and initially didn't see the point to them (the advertising showing a bloke cutting roof battens didn't help show its capabilities off much) but then I saw David Stantons Youtube thing. Bought one and what a great tool it is.
I have to unload and load my tools from/to the van every workday so I can't stand the big numb sliding compound mitre saws, I just have a small light Makita but for a greater length of cut the HKC is a real timesaver.
Plus I have a TS55 set up for ripping sheets and the HKC for crosscutting. Great for making up pipeboxing.