As was explained to me in another thread, the idea behind Synchron is to have an orchestral set up right out of the box. So you load your template and everything is already set up and ready to go. You don't have to mess around with panning, reverb settings, tedious keyswitch programming, etc. However, there is enough flexibility with the player to take your time and be a little more creative if you'd like.
Think VI Pro, VE, Sample libraries, Plug ins (Vienna Suite), and MIR all rolled into one application. Now if you want to do more intricate customized work then you would be better off with your VI, VE templates but if you're a film composer who needs something on the fly and needs it yesterday then Synchron might work better for you.
I don't know how VSL prioritizes the libraries or why they create a dedicated Synchron library (like the SY Strings or the Yamaha Piano) while other libraries are "synchronized" My guess is that it has something to do with being cost effective; you don't have to hire more musicians to record brand new samples and all the man hours that go into those sessions? But I'm not sure.
What I would like to see is a Synchron update or extension to the Vienna Suite for a Convolution Reverb. But they do have a Synchron Room Pack for MIR:
https://www.vsl.co.at/en/Vienna_MIR_RoomPack_Bundle/RoomPack_6
Price: 210 Euro
This is useful because then you can get your VI Libraries and Synchron to match sonically.