Well Cap't Dan, I agree...a breakdown on a trip is more than inconvenient.
I just cannot imagine that the Green Bay outfit did a poor job of repair on the BMW driveshaft. We just don't know enough to make an educated guess.
If it were me, I would call them and explain your concerns and point them to the post dealing with the driveshaft failure.
If I ever need driveshaft repairs, I'll be speaking with them before I decide which repair shop to use.
I'll bet they would like to see the failed shaft and determine the mode of failure.
Here is what I would ask:
1- Do they offer a warranty on their work? What is the source for the parts they use?
2- Are there any particular challenges to performing a reliable repair on these BMW shafts?
3- Do they repair the shock rubber portion of the shaft assembly?
4- How do they balance the shaft after repairs?
These are all good questions that they should be willing to answer.