Yeah +1 on buying from a trusted source. Someone who will be will to select one for you based on what you want. I bought from a source that not alot of people would say to buy from just because there was a falling out of members and the seller. I won't mention names.
Anyways I told the guy what I wanted and how much money I had. He came back with exactly one stone. I bought it trusting him. It is wonderful. I can put a smooth edge on it like plenty of my other naturals. It's fast when I need it to be and slurries well with a slurry stone but doesn't auto slurry with just water. It's thick and will last forever. I can go from bevel to finish in 20 to 30 minutes and that's with refilling my scotch in the middle. I still usually set the bevel on a different stone though but it can be done on it.
On the other hand I have a vintage natural combo that I only use for knives. It is too rough for a razor and the bbw side of it gives a better shave. So there just an example of the huge variances that can happen. You can clearly feel the difference with your hand between those two coticules