Speed, performance and smoothness of edge the Coti wins for me. I have one glued combo and one older slate back. I never use the BBW side of the one. If it was a slate back I would be fine with that.

That being said both my Coti's are different. One is very yellow and a great smooth finisher. The other has a ton of red in it and cuts very fast (when it has a heavy slurry it cut like my 1000k stone) The both finish good, but I prefer the edge off the more yellow one (if that makes any sense )

The reason I say this is because natural stones (even ones mined from the same quarry and material) will preform different, but overall the coti will perform and it's been proven over time.