Got her back...testing begins
The tech worked late friday and came in early Monday(yesterday) to finish the job after the parts arrived on Friday. I had 200 miles on the car by last night, and apparently all is well at this point. I kind of think that the techs and service reps will be glad to see this solved finally. I looked in the rear view mirror as I pulled out of the dealership and saw...4 techs, 2 service reps, and 1 GM standing and waving goodbye...I think they were cheering!
In all seriousness, it's unfortunate that it took so long to find the root cause (I hope), but I'll drive it for a couple or three weeks to make sure that it is fixed before I break out the champagne.
Thanks to all for comments, suggestions and support.
A mercedes is an inanimate object and therefore must respond to logic and reason.