I have had engine vibration just above idle, which appears just over 1000 rpm, is very noticeable at 1200, and diminishes as revs approach 2000, but not sure it ever totally goes away. Tested with vehicle at rest, clutch in or out.
The BMW rep witnessed it and deemed it not "normal" but had no clue as to cause or how to address. I recently was in to have the DSC off function added, and asked again about the vibration. This time the following notation appeared on my service invoice/receipt:
"See notes on previous repair order. Removed engine underpanels to inspect the vehicle. No visual defects were found in the vehicle. No faults are stored in the vehicle. Tested another M5 manual transmission. The same vibration is apparent at 1200 rpm. This vibration is not a defect in the vehicle, this is a characteristic of the V10 Motorsport engine."
I will stop this week to witness the M5 they say does the same thing. However I have driven several M5s and not noted this "normal" vibration, though several of them were never simply tested with vehicle at rest (otherwise the vibrations get lost in whatever else is going on). I think BMW does not want to explore the issue (like taking the engine apart and balancing the flywheel, crank, etc.).
I am willing to live with it, if BMW will back future problems resulting from the issue. For example and out of balance flywheel or crank could put stresses on bearings that eventually could lead to their failure.
I am hoping you 6 speeders can try slowly increasing rpm from idle up to 1500 or so, and see if you have any apparent vibration. This can be felt in the seat of the pants and is significant enough for passengers to ask what it is about.