Synchron Instruments and Vienna Instruments rely on different approaches to sampling. While SI were recorded in place and come with (what the lingo calls) "baked-in" reverb and positioning/panning, VI were recorded centered and without noticeable reverb.
The latter approach lends itself perfectly to very flexible (and malleable) setups with tools like MIR Pro, but it needs some manual adjustments. The former approach is easier to start with, but it's very hard to change the sonic fingerprint of the recording.
To use SI in MIR Pro I would suggest to use the close-mics only. This will allow MIR Pro to apply its magic to a certain extent.
HTH,
/Dietz - Vienna Symphonic Library