One reason I decided to go with the corded Mafell version instead of the HKC was the rather weak looking rip capabilities that the "Mike's Tool Show" video seemed to demonstrate. This type of saw allows for some real flexibility/versatility, and that is what sold me on the concept. Making it cordless adds some advantages, and gives up some too.
As I see it this type of saw in a corded version shares much of the same capabilities as a regular circular saw, track saw, miter saw, radial arm saw and table saw. This gives it tremendous versatility across a pretty broad spectrum of different types of work. As Phil already mentioned, the HKC is more crosscut focused. My thoughts are the HKC, as is, loses some of the versatility being an 18v cordless system. Reports seem to say the TSC55 can eat batteries, and it uses two. What can the HKC do with one?
I'm not sure I'd be ever be truly happy with the one 18v battery of the HKC. I haven't used the tool so I'm certainly not seeking from experience. We'll see pretty soon as these make their way to the hands of real world users.