What's the problem in answering these questions? I just want to understand why specific things are done this and that way. I don't question VSL's mixing engineers, they should know what they're doing, shouldn't they?
I'm interested in these technical things, because VSL is different to other developers: For example, they provide the tree signal separated in LR and C, which no other developer offer. I also know that VSL uses other microphones with a different sound, the majority of other developers uses Neumann M50s. Of course, it's great to have all the flexibility the signals offer, but on the other hand it makes things more complicated for inexperienced users.
Also: The mixes are not unified across the board, and the same is true to all the SYNCHRON-ized libraries. The mixes are done with different mixing engineers and their sonic preferences. Some use room reverb, other use plate reverbs etc. Dietz's MIRx settings sound different to the SYNCHRON-ized libraries, too. For example we have three different settings for the Appassionata strings: in the SYNCHRON-ized SE, in the SYNCHRON-ized library and with MIRx. In my opinion, they should re-work this and make everything the same. But that's another topic.