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Sounds like some of these "facts" came from a ricer mag. Facts are physics, and here goes, sorry for the length...
Brakes work by converting kinetic energy of moving the car to heat through friction. The ability to stop is determined by the limits of the ability of the system to take in heat. This is the thermal capacity of the system: ie the point at which the system fails from overheating. This is determined by the mass of the rotors themselves, and so you want as much metal as possible in them. For Supras, we have rather wimpy brakes to begin with, and so drilling takes thermal capacity out of them and makes them worse than before.
As to the purpose of drilling...it used to be gas and moisture dissipation. No longer. Pads don't gas off as they used to as the materials have changed from organics to composites and metal matricies. Now, it is done (when it is for a reason other than looks) to reduce rotating mass where there is already an abundance of mass for stopping.
As I can see the question "why does porsche use it then" coming, I'll answer that one now. Porsche rotor diameters approach 14 inch on some road vehicles. They gain excess mass through diameter and thickness of the rotors. They actually have much more thermal capacity than needed for the intended use, up to and including mild track events. Hench, they drill to reduce the mass of the rotor. Remember the worst kind of weight is unsprung or rotating, and this is a part that clearly qualifies for both at the same time.
If you watch a racing series such as the ALMS, you will see that different tracks even have the teams change from drilled to flat rotors...those are the really heavy braking ones and they feel the need for the mass.
In a perfect world, any mass added that can take up some heat helps us. In our imperfect world, unless you upgrade to big brakes, forget the drilled, unless you are about the bling.
Now for slotting, the facts presented are correct to an extent. It does scrape the pads, but at all times, not just high heat. The extra friction of the slots sweeping actually can induce thermal failure as the pads get hotter than normal, faster. If you run higher temp compounds on the street, you can often make them quite normal feeling by slotting. High heat pads tend to have little grip when cold. I do this myself, as it allows me to run higher friction pads that require a little more heat to work properly, and I build a little more temperature tolerance into my brakes. Downside is pad wear, and the greater chance of warping a rotor or boiling fluid as you do run them at a higher than designed heat. Pads are cheap however, and rotors don't warp often. Change fluid annually and it should be fine too.
Bob
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