I have looked at synthetic progressions and used a number of brands over several years. And I also take a bevel and edge to a pretty high finish prior to going to a natural finisher, usually a Jnat or Ark.

To me the brand of stone does not matter for the bevel setter 1-3k. I usually use a King or Nubatama. All I want is a stone that will shape the edge quickly and leave an even shallow-ish stria pattern. I do not like using diamonds to set a bevel but use them for edge repair.

The following stone, once the bevels are shaped and flattened is just to remove all the deep 1k stria, I am not all that concerned about the stria pattern as long as the deep stria is removed. It can be 3-6k. I call it a transition stone, because I transition from grinding/shaping to polishing/refining the bevel and edge.

For the last few years, the next stone has been the Naniwia 8k Snow White. It is aggressive, easily removes 3-6k stria and leaves a near mirror finish, occasionally there are random stria, that I do not worry about. The bevel is smooth enough that I can easily build an Ark or Jnat Kasumi finish on without having to deal with deep bevel setting stria.

I do not have an 8k Shapton, but have a 16-glass stone, it too can leave a near mirror and is aggressive enough to remove 4-6 k stria.

For me, the goal to a pre natural finish stone is removing 4-6k stria and leaving a near mirror finish and straight edge, whatever stone does that.

I have an old King stone, that I think is an S-3, 6k. That stone is very soft, muddy but aggressive and capable of near mirror finish. I have been wanting to make a post about it, as I recall years ago King was making stones on wooden dai that were a blend of synthetic and Jnat. I think this stone may be one of those. It is light brown with dark brown speckles on a King type wood dai and smells of mud and tobacco. I sometimes go to a Jnat from that stone.

I will try to take some pics and make a post next week.

Back to your post, it is much easier to produce a nice Jnat finish and edge from a near mirror bevel.