I have over 70K on my 99 and have yet to change rotors...probably will on my next brake pad change...that would mean a rotor swap for every third pad replacement interval.

Pads on the ML are a "press fit" versus a slot fit on earlier MBs...that is, they clip onto each side of the calipers via pressure clips. Because of this, the calipers have to be removed in order to access the pads.

The rear calipers can be unbolted with a socket wrench (can't remember size). The fronts require a T40 torx socket.

I did my last pad replacement in about an hour (including jacking up, wheel removal, etc.)

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car