Remember BMW techs opinions come from working in a dealership, where they should do no wrong (else suffer their manager's wrath), and where more than 50% of the cars coming in are new, and most of the balance are there as they have a problem already.
I don't feel that such opinions are statistically accurate for our cars- they are not the same demographic (i.e. how many 20yo Bimmers get serviced/fixed at BMW now?).