I have been turning drilled and slotted rotors on old fashion ammco brake lathes for 25 years and this is the first time I heard anyone tell me you can't do it, I have even done it on fancy BMWs and stuff that come from the factory with them and have service limits published (most wear out too fast but occasionally you get some that are not worn too far). I guess I need to go back and call all those customers and re-do all their brakes for free now.

Now that I said that I see no benefit to them as it reduces surface area that you need for braking. Unless your upgrading the size of the rotor to make up for the lost surface area I sure don't think they are gonna help anything and more than likely make it worse. Those cars that come from the factory with them all have huge brakes already to accommodate the loss in surface area. It is just a sales gimmick for your truck.