wilbur
On the old western wooden planes that I've looked at, many of them had convex bevels as they came to me. However, the convexity didn't seem to affect the effective bevel angle. The convexity seemed to be more a tailing away of the bevel as you went up the bevel away from the edge, as opposed to an increase of the angle at the cutting edge.

I wound up putting a flat bevel on these blades, but in checking the bevel angle with a gauge before doing that, all of them have been in the typical 25-30º range. There may be reasons not to have a convex bevel, but compromising the clearance angle doesn't have to be one of them.