I've also tryed shaving at the 8k i have been using norton 4k/8k for 2 years now and i have never shaved of the 8k.
So i gave it ago and guess what no problem infact i think for the every day shaver like my self that is all you need. On my second shave this morning i have aded the coticule with water 75 laps yeh probably a little smoother but not much and defanatley not sharper i have 12k kitiyama i think i will try the same routine but with 12k kitiyama and compare. To be onest i have two coticules one bbw and 12k kitiyama .You have to try differant hones and if you don't need them you could easily sell them but i realy think the norton is ideal and all you need unless you hone razors for living.