I invite you to come to the left coast side of NA and try it out on our rapid changes in elevation on heavily trafficked ice covered mountain roads. What kind of grades are you referencing?
Downhill is not a fun proposition feeling a tire loose traction for any amount of time, especially when not expecting it. Being off line by a foot can change the outcome of your day quickly. I know my current vehicle excels there, but it doesn't incidentally lock its tires under its own control, and totally inspires confidence even in those conditions.
If anyone has intentionally tried to lose traction explicitly from regen on ice (to better understand how the system is reacting and what it will do), on common downhill highways with steep/Very steep grades around mountain passes, maybe even goat tracked highway roads where snow is falling and building up faster than it can be removed, would love to hear feedback.
Is that an issue where the car can step out unexpectedly? Obviously the pedal "can be" modulated to prohibit regen, but that's Not the question, can regen be so aggressive as to put a person off line and the problem "snowballing" out of control because the car was being too aggressive putting the driver off line even if briefly? Possibly before it detects a slip and changes to a snow mode setting, or even while within the automated snow mode period of time ?