I don't think the issue is with BG products, it's with a dealership upselling services the customer likely doesn't need (nothing new) and not using BMW approved fluids, which is abnormal for a dealer.People love Amsoil and Redline who skirt around approvals. Why is BG any different?
FYI, I only buy lubricants with actual approvals. The thought that third-party testing has taken place gives me peace of mind.
The BMW dealers around me aren't great, and are definitely the type where if you used non-approved oil and had a warranty issue they would fight you over it, which is why I find this whole thing interesting. Like I stated before, the only thing I'd be a bit concerned about is the X-Drive fluid, just because the specs seem so specific for that fluid, but otherwise I wouldn't worry. I wouldn't change out the diff fluid, that would be a waste of money and time for a gain of possibly .2 mpg.