I have the king stones. I have not had the same problem with the Nagura. I have switched to using 325 grit sand paper to slurry them, although sometimes on my 8k I slurry with a coticule bout when I don't want to go through a coti progression. Overall I have found my king stones to be acceptable starters. I have recently purchased a Chosera 1K and a Norton 4/8 to round out my combo coti, king 800/4k, 6k, 8k and a C12k. Yesterday I lapped the Norton, which can I just say I was surprised at how much stone you have to remove to get a smooth finish. I took my Russian to the 8k as it had been tugging a little. Today I shaved with it, a world of difference from the king. I have made many razors shave-able off the king, but I felt there was a noticeable difference between edges. I think I am developing HAD...be careful brother, its a silent (bank account) killer....
Good luck and I cant wait to hear more about your progress!