You can get a good shaving edge off the 8k, though the 15k is awfully nice. But I agree that it's complicating things for you - you need to get a handle on the 4k and 8k before you worry about the higher grits.

BTW, I did popped a wire edge off into my 15k a week ago (that Koeller ) and finally got the last piece of steel dug out of the hone the day before yesterday. Lots of tweezing and microscope work... Those hardwood paddles have really made me sloppy, and it's gonna take awhile to work through it.