It would be a nice knife stone for convex bevels.

For razors you could use it and very slightly convex a bevel, but a razor is so short width wise, (1/2 -3/4 inch) it would not convex all that much. Especially if you only use it as a finisher. Most folks only hone on about 4 inches of stone anyway.

It would be an interesting experiment to see just what it does to a bevel, hone it on a flat stone and measure the bevel, then finish on the Coticule side and see how much it changes.

What does the BBW side look like?