There seems to be an obsession in recent pages of this thread with the depth of juice channels on these Kayfun clones.
Yes, obviously if there are no juice channels at all, or they are almost non existent then you will run into some wicking problems. However, I think folks overstate the importance of the channels themselves. What really matters are that there are channels and that there is enough depth where they meet up with the chimney for the vacuum to pull juice into the chamber.
As I've said before, I have multiple authentic KFL+s and R91s as well as multiple Black Editions. There is a visual difference In the depth of the juice channels on the Black Edition vs the authentics. HOWEVER, there is no difference in the way they vape for me, even when running a pretty viscous 20/80 DIY liquid (no water or alcohol added). Mind you I'm run mine with the AFC wide open as well.
I can't personally speak to running a liquid with a higher VG content than 80%, but for the vast majority of people having problems (unless maybe you're using 100% VG) they're problems likely have more to do with build/wicking than with the depth of juice channels.
I'd be very leery of buying a clone that's advertised as having "deepened" juice channels. SvoeMesto (applicable to the makers of the Russian as well) clearly spent a lot of time and money engendering all aspects of the Kayfun line to perform as well as possible. Everything on the originals is machined to precision, including the juice channels. It's clear to me that the calculation by the Chinese is that since they are mass producing these clones not exactly using precision machining and that you can get away with slightly shallower channels, that is is better to err on the side of using a shallower channel than spec a deeper channel and have devices that constantly flood and pour juice everywhere.
If you are that concerned with the depth of the juice channels, I wouldn't count on a Chinese clone that has them to not just flood, and flood, and flood because they ended up being too deep and open. Instead, if this is really a big concern, go out and buy an authentic KFL+ or R91. Sure, it'll cost 2-3x more than the clones, but you won't have to worry about juice channels being too deep or shallow for your liking.