I use a 1000 grit and a 8000 grit stone, and like you said, I have tried many other methods including sandpaper and others, but my two bench stones do the majority of my sharpening. I get great results using just the two stones that I have. The 1000 grit stone cuts pretty quickly, so that stone, being the coarser of the two does the majority of edge reshaping that I need done. Then I finish it off with the 8000 grit stone to produce a hair popping edge. I don't believe there is a need to get that many different grits for bench stones. I've recently started using a leather strop loaded with green compound to finish off a few edges, and I still use sandpaper once in a while if I want to convex an edge, but I have not yet mastered either of these techniques so my results are only satisfactory to this point.
In my opinion, a 1000 grit and an 8000 grit stone can accomplish most sharpening needs. They are not ideal if you need to cut away a lot of steel, such as fixing a chip or broken tip, but they can do the job. I don't have any mechanized equipment in my sharpening arsenal at this point, but I have had a lot of my restaurant/chef buddies ask me to touch up their knives for them, so I was thinking about adding a belt sander at some point to speed up some of the edge re-profiling that needs to get done.
Also, Murray Carter has some excellent sharpening instruction out there, and he uses the coarse stone/fine stone method. Just two stones, no strop, and that's how he finishes all of his blades, and then he shaves with them. Machetes, neck knives, axes, everything is finished in the same method, and he can get the same results with just two grits of water stone.