Soon after purchasing my '73 350SLC twenty years ago, I replaced the brake pads. At the time my brother was able to get me some metal pads (Hardies) at a good price (in fact he got me 2 sets!). The rotors were fairly worn so I figured it would not matter if the pads damaged the rotors and I had to replace them, it was an opportunity to try the pads. I was impressed. The pads did not have quite the "bite" of the OEM pads but they were still more than sufficient to brake to the point of locking wheels even on good surfaces. Hot they resisted fade and remained strong. An added advantage was that they were fairly clean and the small amount of dust produced was a grey colour that did not show on the silver wheels. The fronts eventually wore out after 112,000km at which point the rears were still only half worn (yes, 112,000km)! What's more, the front rotors had only just worn to their minimum thickness at this this stage. I fitted new front rotors and the second set of front pads and they continue giving good performance to this day.
When we purchased our '90 300TE I wanted something to replace the filthy OEM pads. A friend in the brake business advised against metal pads (which I wanted following my good experience with my SLC) as he claimed my wife would not like the lack of bite of the metal pads. Unfortunately, the Hardies brand metal pads fitted to my SLC were no longer available. He supplied me with Bendix "Standards". They are very clean producing virtually no dust, however they have a low maximum temperature rating and with only a small amount of vigorous use will fade badly. I also feel they produce no more bite than the metals in the SLC, certainly less than OEM pads.
When I recently purchased my '90 190E, again I was looking for a solution to the filthy wheels (that I removed and spent many hours cleaning inside and out). The previous owner had fitted dust shields to the front wheels which at least keep the outside clean but the inside still gets filthy. The Bendix "Standards" are no longer available due to asbestos no longer being used. I have tried some Bendix "Euro Pack" but they seem as dirty as the OEM pads. I enquired with Bendix if they could recommend something cleaner that would still offer good performance. They claimed that none of the current range are as clean as the old "Standards" but their "Advance" are the next best and offer better resistance to fade than the old "Standards". They sell others including metal pads but claim that these are not as clean as the "Advance". I have yet to try these.
Despite my preference for OEM products, I cannot put up with the filty OEM pads. Not only do they leave wheels looking dirty but the dust contaminates the suspension and underbody and even leaves a black film along the lower panels of the car which can soil clothes. I like to keep our 300TE in showroom condition (it usually wins its class in concours despite being a daily driver) and now I want to bring my 190E up to similar condition. This is not possible in a daily driver with OEM brake pads.
107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.