Slots/drills won't affect off-roading.
Slots are to help remove water more quickly via the slots.
Drilled are for extra cooling but in my experience (won't buy drilled again) they make a low frequency drone sound and I can feel it in the pedal too. Just an odd feeling.
If you want better cooling look for angled vanes as opposed to the standard vanes which go straight out from center outward. Angled vane rotors are side specific so they point foward to grab air as they turn forward pushing it inward cooling more effectively than standard vanes. Extra cooling is sometimes needs with mountain/hill passes, towing, stop/go, ect.
My favorite brands are Centric and Powerstop:
Performance Brake Upgrade Kits for Sport, Utility and Daily Driving | Power Stop Brakes
Luck and enjoy the Runner.
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2001 Limited 4WD - 346+K - SunfireRed\Thunder Cloud; - 265/75/16 Michelin A/T2s - Fat Pat's 1.5" BL - StopTech ANGLED rotors - In series 699 trans cooler, New Yota1 transmission, All new OEM suspension front to rear.