Hehehehe People tend to put way to much faith in "Grit Charts" that are at best inaccurate and at worst downright deceptive...

The Shapton 8k is without a doubt a higher grit hone then the Shapton 6k

and

The Norton 8k is without a doubt a higher grit hone then a Norton 4k

How the Norton 8k and the Shapton 8k relate to each other in grit ratings is very much in Doubt toss in a few more brands of 8k and that whole grit chart gets very doubtful...

Yes you should be able to shave quite well off of the Shapton 8k

Here is another fact that I have no doubt of "The more razors you hone, the better your edges will get"