Welcome Bat,
great to have you here. :-)
While Vienna Instruments and Synchron Instruments share the same ancestors, they are not twins. Synchron Series is not simply "more of the same", but based on a very different approach to the same objective: virtual orchestration.
The whole concept of MIR is firmly based in the camp of Vienna Instruments and its underlying principles: no pre-recorded reverb, no burnt-in panning, no multi-mic setups, but every detail and aspect freely shapeable. MIR works best with input signals like that: pretty dry (at least without reverb), ideally in stereo, but centered.
Synchron Instruments _can_ be set up this way to some extent, too, but truth to be told - you would be using them against their intended purpose. The spot-mics that are part of the many, many mic positions of typical Synchron Instruments will often supply a surprisingly dry signal, still they are hardly meant to be used on their own: You'll miss out on the biggest assets of this great collection if you turn off the room mics.
... as a bridge between VI and SI we came up with the so-called Synchronized Instruments. Based on the recordings and concepts of the original Vienna Instruments they come in a fresh and (partially) remastered version that relies on VSL's Synchron Player instead of the trusty "old" Vienna Instruments Player, presented in a ready-to-play fashion out-of-the-box that matches the sound of Synchron Instruments perfectly. In this case it's an absolutely valid workflow to switch off the internal spatialisation of the player and to use MIR 3D instead, which offers a vast selection of beautiful and distinctive halls and stages.
Hope that helped,
/Dietz - Vienna Symphonic Library