I still use metalmasters because they work. For me they are a known quantity and even after 30 years, or maybe because of 30 years with 'em, I've not had any reason to change. But their availability IS getting impossibly hard, just like good rotors. Repco ->PBR->AXiid pads. I'll be watching this thread to see what others use now.
I too have used MetalMasters on several early 70's BMWs - for decades. Found the so-called "deluxe" (semi-organic) friction materials to be less suitable than the MMs. The former seemed (in my opinion) to require greater braking effort when warm, created significantly more brake dust and seemed less durable, i.e., shorter lived. Although it may seem counterintuitive, I think the rotors experienced a longer life with the MMs, too. MetalMasters, like all friction compounds are a compromise. When left installed against brake rotors in moist/humid conditions, they can exhibit or develop rust. Since the same pad shape and style were used with the tii and early E12 and E24 models, I suspect that semi-metalic MetalMasters are still available, but perhaps with different branding.
The fact that the original poster can hear his brakes initially suggests that the pads have not conformed to one or more rotors, but any number of things can cause brake noise. This includes out-of-round or imperfect rotor surfaces, loose wheel bearings, loose calipers, or even the mounting of the pads in each caliper. Bear in mind that shims were often employed between the caliper pistons and the brake pads to limit heat transfer and to mitigate pad resonances and resulting noise. Many newer pads have materials on the backside that effectively limit pad movement and render backing shims - unnecessary. It should also be noted that many newer pads have chamfered leading and trailing edges to permit faster wear-in. (Cannot offer much personal advice regarding the spate of newer "ceramic" friction compounds that were not available when E9's were new.)
for illustrative purposes, note chamfered edges.
