OE consumables are made by 'pattern part' manufacturers anyway because they can manufacture them cheaper and they are supposedly the speciallists in their field. I know that the OE brake pads I used to buy for my F650 were made by Brembo and stamped BMW.
If you buy quality 'pattern' parts you can often surpass OE quality. Just don't buy rubbish.
However, one benefit of buying things like OE pad kits is that you often also get replacement squeal shims, pins and circlips.
If BMW parts are so good, why is this forum so busy?