well by adding ridges you would effectively be increasing the area of contact between the core and the urethane, so therefore it should be able to adhere better. that's just from a physics point of view but w/e
you wouldn't buy metal cores just based on the fact that the core has ridges on it. it depends on the quality of the adhesive, the urethane and the core itself. If I were buying new wheels I'd just get protos from moonwalk or eagles