I run one of the largest independent repairs shops on the east coast & spend 30+ thousand with BMW OEM, 18+ thousand with OE parts each month. I have not seen any specific decline in BMW OEM parts in the past 7 years at this facility. I can tell you this, with experience I know which aftermarket or OE parts to buy vs BMW OEM. Example, I have had multiple OE valve covers for M54 & N52 fail sub 1,000 miles since install & would only go with BMW OEM valve covers for any car that comes through our shop. This is just one example of hundreds but you get my point. In that same breath, for the GS7D36SG DCT transmission, URO & other OE transmission pans w/ gaskets are on par if not better than BMW OEM. I wouldn't expect most hobbyists to have the similar experience with this as someone who works at a repair facility but OE aftermarket parts should not be thrown to the side as lesser quality / value than BMW OEM.