I bought a 80 and 220 for my 6 inch Cab King, they last a long time. One thing I like best is after shaping on my 80 grit, the 220 grit does a beautiful job of smoothing out the waves, better then the 220 wheel by diamond pacific in my opinion, it has extended the life of my 280 Diamond Pacific wheel greatly. I am extremely happy.

These wheels are amazing for the price. Beautifully machined, well balanced, and smooth cutting. I have the 8" in both 80 and 220 grit, and they pair perfectly. It is an easy and relatively fast grind on the 220 to remove the scratches and refine the shape left by the 80. I also have a a few sintered wheels from other manufacturers, and some seem to have a higher concentration of diamond, (and price) but they don't really cut any better. So my conclusion is that the diamond in these wheels is sharp and free cutting. I can't speak about their ultimate durability yet, as I have only put a few dozen stones (agate, jade, opal, jasper, and tiger iron) through them so far, but short of using a micrometer, I cant see any wear, or change in cutting action.

I would say that a slightly coarser wheel would be nice for doing bulk removal and roughing in harder stones might be nice, but as always, there are trade offs with chipping and sub surface fractures.