Coarse SiC paper reportedly wears faster than AlOx paper because the particles are more friable and they break up into finer fragments than AlOx.

So, how does this work with bench stones? I have two bench stones I bought years ago; a 10" cheapie AlOx combination stone that cost me about $3, and an 8" SiC combination stone that cost about $30. The SiC stone cuts a lot faster than the AlOx stone when I sharpen the kitchen knives. Is the difference because the stones are in a solid mass that resists particle breakdown better?

I use these stones handheld under running water. Should I be doing this differently? Seems to work reasonably, but rounds the edges a little because it's handheld and they are starting to dish. Well, the SiC one is; I haven't used the AlOx one for ages.

I also have a large natural combination stone (8" x 3"), which looks like a dense sandstone on one side and shale on the other. The shale side gives a nice polished edge, but it's very soft so wears quickly. Should I use water or oil on this? Lots or a tiny bit?