I agree with Paul. That's why I now have diamond stones, water stones, oil stones, strops and compounds. :?
Actually I use them all in different situations and for different tools.
Just to address the watwer stone flattening issue, for me the key is handiness. That's why I use a big diamond plate to flatten my water stones: it's quick and relatively hassle-free. I also use the stones' relative softness to my advantage: depending on how many blades I have to sharpen (usually at least 4 or 5), I start out with the blades I want a straight edge on (block, jointer), then I go to my smoother, then to blades with more camber (fore, jack). Then I might reflatten once (it only takes 20 seconds or so per stone) to do chisels or other small blades.
You can polish an edge on the wheel, I've seen tons of info on this forum about that (Jake Darvall for example) but I don't know how it would work to flatten or polish backs (?).
Norton 8000 stones can be permanently soaked, but you can also just fill your container with the right amount of water so about half a stone soaks while the other (top) half doesn't.