You may not have to dismantle the headliner in order to remove the sound insulation panel(s), (I also have a black ML...in "balmy" Texas)
but in order to replace the panel(s), the headliner MUST come off! Going without the sound insulation panel will make for a noisy ride, especially if the moonroof is open.
The residue is hard to remove w/o some acetone-based cleaner (such as Goof Off), and every time you open the moonroof, it will make contact with the backside (sticky side) of the sound insulation panel(s) and return with another layer of glue.
My door panels did this first before the moonroof...fortunately, the factory warranty covered both.