I found some pads that would be worth a try. EBC greenstuff series 6000 has a pad for the ML. The literature claims reduced rotor temps, shortened braking distances with increased g-forces. I had these on a BMW. They are also a low dust pad. Cheaper and easier to swap than rotors, may be worth your while.

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1995 G320
1984 280GE
1971 Unimog 416