Stick with your Grise for now Jim. I know bevel setting can be a pain on it, but after you can max it consistently then you might want to try a new stone.
I love Coti's, and each coti differs to a degree. The beauty of the stone to me is that 2 exact same stones, same in size and vein, will yield 2 differient edges. They will be the same as what is expected from the respected vein, but each will have it's own signature to the edge. I guess that is what intrigues me so much about them.
If you want to just stick to the coti and want to set bevel faster, you might look at a less inexpensive bout that is fast on slurry. Reguardless of what you bevel set with, if you run the dilucot on your grise that will be the characteristic the edge will have.
Sorry for being long winded.
Just because it's sharp, does not mean it's smooth.