Originally Posted by sweeks

I have had the opposite experience, fortunately. The cones are under somewhat higher "specific loading" because of their smaller radius of curvature. This explains the tendency for the cones to deteriorate first. Of course, if the bearings are not correctly adjusted, poorly lubricated or contaminated by dirt, both surfaces may wear prematurely.
I have a couple sets of wheels that are on their second or third set of cones, but the outer races are only polished smooth. Luckily I serviced the bearings in time!