Vacuum leak at dipstick would be all the time and affect both banks.

Yes, leak down test is opposite of compression test but does check more that just leaking valves. It is a long shot but---

IMO smoke test was not conclusive.

That said, your focus should be on correcting the fuel pressure bleed down. Rough idle could be symptom of fuel pressure issue.

__________________
X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas