You can buy dust free brake pads. You can haul the Metris down from 101mph with surprising efficacy. You can’t do both.
The brakes pads used by MB and some other European Marques are designed to maximize stopping power- particularly from high speeds- at the expense of both life and brake dust. That’s not me being an MB fan boy; that is simply a relevant fact. You can solve the brake dust problem by switching to longer life, less dusty pads- but you will pay a substantial price for it in braking performance. That is up to you.
Some additional advice: the Metris has, by far, the best performance, high speed stability, and handling of any Van on the American market. That, and it’s safety performance, are why you should buy a Metris over a short-wheelbase, low roof Ford Transit 150. If you are not using that performance, such that sacrificing Braking capability for other things is actually something you would consider, I suggest you trade in your van on a Transit. You are paying a huge premium in servicing costs and maintenance headaches for something you aren’t actually using.
Thats not being a fan boy; that’s honest, straightforward advice.