Overdue for an update here. Will post back a case summary with full details later. Right now a quick post to tell you all I found my issue. I indeed have oil in my brake booster. Three calls to BMW North America and one to the dealer everybody swore up-and-down this car was not involved in the recall for oil and brake boosters, seems to be a different story and the braking system in the 4.8is matches many of the other cars that were involved in the recall.
At these now I know the new booster should fix it.
A few weeks ago I did change the vacuum pipe between the vacuum pump and the booster. Of note my pipe was completely dry however the one-way valve and it was toast. New vac line from BMW actually contains two one-way valves one at the booster and one midway
Junkycosmos
2005 X5 4.8is