True, the better quality slotted rotors have slots with more of a radiused edge and angled wall than just a sharp corner. But, it's still a flat rotor surface that meets a void. The pad material, on a microscopic level, is still deflecting (being "squished") into this void. The harder the braking- the more that is squished into the void and the more material that is shaved. Yes, this provides more friction. But the primary function of the slot is to evacuate the gasses and heat formed under braking while channeling in ambient air- all which help to cool the rotor and pad which prevents glazing, fading and warping.
I'm a believer in their function. Years back, when cryo-tempered rotors were new to the general market, Powerslot teamed up with a cryogenics company to produce their "Frozen Rotors" line. I had one of the first, if not THE first set on my S10. I was a total ******* to those rotors for 11 years/70,000 miles until I sold the truck. Went through 3 sets of Hawk HP pads (never turned the rotors). I could stand on the brake pedal from 120MPH+ and never get so much as a pull or shimmy in the steering wheel and the brakes bit just as hard as always. The last 20,000 miles I had the truck, the pads were being squished even harder by a hydrabooster. The only thing I ever noticed after all this braking asshattery was a notably heavier coating of dust on the wheels.
I'll use my soapbox time here to give my review on PowerStop rotors. I thought the cryo-tempered rotors from PowerStop were the same as the Frozen PowerSlot. I don't believe they are, or maybe the quality of the base rotor is less. I think PowerStop, PowerSlot, Stop Tech, etc. are all one and the same, using Centric rotors. Assuming I was replicating what I had on my S10, I installed some cryo-tempered PowerStops and Hawk LTS pads (LTS since it's a full-size vehicle). I performed a break-in process by combining PowerStop and Hawk's recommended procedures as they were a little different but not really conflicting. The brakes felt great with more bite than stock and the warping was gone. A few days later, I drove to Tampa, Florida. While slowing down to a red light, the damned warping was back. I hadn't done ANY hard braking. It was less than 1,000 miles, 800+ of which was interstate driving with no brake use, and no hard braking before they started their bucking shit again. I keep seeing positive reviews on R1 rotors so I think I'm gonna give them a shot. These bite great and all, but I can't stand the feelings of warped rotors.