x-drilled/slotted will not warp any where near as easily as oem because htey remain much cooler due to the holes and slots. For me that is a huge buying point.
But what they also do is they allow the gas to be released as you know. With oem rotors there is a layer of gas between the pad and the rotor which does not allow it to stop as easily as a x-drilled/slotted rotor. However, as you know the down side to this is that the rotors and pads have much more contact and therefore eat pads a little quicker. However, I have not heard that the pad wear is bad enough to not get them.