I just got one 2 wks ago and already used it to record a live concert. I burned the CD and it sounds absolutely awesome.
Before I got it, I read up, then talked to some studio engineers who I respect. I only heard good stuff. One guy said that he thought it sounded better than the Yamaha AW4416, which I had already heard sounds better than the Roland VS2440. For me that was a clincher. At a much more reasonable price ( the Yamaha is almost twice the price and the Roland VS 2440 is almost thrice) the Korg sounds better!
I didn't research the AKAI, so I can't tell you about that.
I also don't care who copied who. I am mostly interested in sound, ease of use, and features.
So, there you have it. Just realize a couple of things about the Korg, and comperably priced units:
(1) You've got to pay alot more for motorized faders. Neither the Korg nor the comparably priced unit from Roland (VS1880) have 'em. Instead, the Korg gives you "scenes" which are fader setting "snapshots" that you can save. Not as good as motorized faders -- but not bad at all. And of course, you can always do standard fading while mixing down. For me this works fine.
(2) The number of simultaneous tracks halves when you switch from 16 to 24 bit mode. This is a little deceptive in terms of their advertising, but what are you gonna do. With the Korg it goes from 8 to 4 tracks for recording, and from 16 to 8 tracks when playing. For me this is still fine.
I say get it, you won't regret it.
Hope this helps.
-jk