Okay, so here is the permanent fix: replace the pads, rotors and sensors. Wow, what a shocker! A PuMA case was opened on this situation and I'll credit my dealership with not accepting BMWNAs feeble attempts to "fix" the problem. My SA said that BMWNA was taking a lot of information (more than normal) and suspects that there will be a new SIB coming that addresses vehicles with certain rotors/sensors/pad build dates and will just say to replace everything.
For those of you who are still encountering this problem, recommend taking the SIBs that are referenced in this thread and you can also quote PuMA case #: 29814970. This should help your service dept quickly cut through all the steps necessary to get the problem fixed properly.
Here is what is on my invoice:
Customer states: ONCE DRIVE FOR ABIT AND COMING AWAY FROM A STOP THERE IS A SQUEAK FROM REAR
CAUSE: PC# 29814970
3421928 Removing and installing or replacing both rear brake discs
170 WB (N/C)
1 34-21-6-791-938 REPAIR KIT, BRAKE PADS
ASBES: 348012 (N/C)
1 34-35-6-789-445 BRAKE PAD WEAR SENSOR: 343030 (N/C)
2 34-21-6-764-655 BRAKE DISC: 342040 (N/C)
42514 REAR PADS, ROTORS CAUSING NOISE ON TAKE OFF FROM A STOP. DUPLICATED THE CUSTOMERS CONCERN AFTER DRIVING THE CAR FOR ABOUT 6 MILES. ONCE THE BRAKES WERE FULLY WARM THEY WOULD MAKE A LOUD HIGH PITCH WHEN TAKING OFF FROMA STOP. INSPECTED THE REAR PADS, ROTORS, AND SENSOR. ALL OF THE CONTACT POINTS WERE LUBRICATED. I DID NOT SEE ANY VISUAL DEFECTS WITH THE PADS, SENSOR, OR ROTORS. I MEASURE THE ROTORS I NOTICED THAT THE OUTER DIAMETER WAS WORN MORE THAN THE INNER DIAMETER. rotor thickness outer diameter: 21.36mm, rotor thickness inner diameter: 21.52mm, pads: 8mm. I CONSULTED WITH THE SHOP FOREMAN AND WE DECIDED TO SENDA PUMA CASE #(29814970). AS PER PUMA, I CHECK TO BE SURE THAT THE PAD SENSOR WAS NOT TOUCHING AND IT WAS NOT. I CHECKED HISTORY TO SEE IF THE BRAKES HAD EVER BEEN REPLACED AND THEY HAD NOT. I TEST DROVE THE CAR AGAIN WITH THE PARKING BRAKE APPLIED (JUST ENOUGH TO DRAG AS PER PUMA) AND THAT DID NOT MAKE A DIFFERENCE. NEXT, PUMA AUTHORIZED ME TO REPLACE THE REAR PADS, ROTORS, AND SENSOR. I REPLACED THE READ PDS, ROTORS AND SENSOR. THEN I TEST DROVE THE CAR NO LONGER ABLE TO DUPLICATE THE CONCERN.