Ok, I've done this mod to 4, M54 engines now.
Latest one was my son's '03 325....he called me in a panic thinking he had blown a head gasket. Temps were around 14 degrees and all the mustard gunk in the original CCV system froze solid. We let it thaw out when the temps got up to the 40s and now he doesn't have to worry. The only issue I have is with my '01, 530...seems there's oil leaking out of the tube which did go to the dipstick. I think I may have a bad oil stand gasket and the oil is running down from that. Again, thanks for starting this thread....