I have 3 complaints with the CKN70s:
1) The overall spectral balance is kind of wonky... they have serious midbass/lower mids, and they are significantly recessed around 2 kHz, which hurts clarity in vocals, guitars, etc.
2) They require some pretty crazy EQ to smooth out the high end (if you want the high end to be smooth... some people don't mind). It's peaky in weird ways.
3) The channel matching was kind of off in mine: sweeping a sine wave through the whole spectrum results in some crazy back and forth panning.
That said, very careful EQ to tame the midbass, boost broadly around 2 kHz, and tame the treble spikes yields probably the most technically impressive IEM I've ever heard... the detail, sparkle, speed, black space, and sub bass are unreal once everything is balanced out to one's liking. These are so much fun to listen to and remind me of a really high-end home theater rig with a subwoofer.
I just got GR07BEs yesterday, and they are very nearly as technically good as the CKN70s to my ears... burn-in will probably make them even better. The channels are nearly perfectly matched. Although the sub bass is not quite as impressive as the CKN70s, the rest of the spectrum is MUCH more balanced. The midrange on these is wonderful and lacks nothing. Although I tend to cut the midbass a little bit, it's probably right where it needs to be for most people. There are still the usual spiky resonances in the high end that cause a little sibilance, but they're much more regular and easier to fix, and to my ears, the GR07BEs sound far better than the CKN70s without EQ. Plus, they're incredibly comfortable, the adjustable nozzles are great for getting the best possible fit, the cable is fantastic with pretty much no microphonics, and if none of the ridiculously many ear tips they provide work for you, you might need a custom IEM anyway.
If you have patience and parametric EQ that you can apply separately to the left and right channels, though... the CKN70s are about half the price and lack nothing to my ears in clarity and ability to reproduce detail. I can't emphasize enough how immersive and captivating they are once the spectral issues are sorted out. I don't think I'll be getting rid of mine.