I would have no problem to record all VIs first (and hear with W2 e.g.) and then, when the mix is ready, make the step and use MIR offline for creating the concert hall orchestra sound.
More important factors for me and surely several other users would be
- the price
- the technical requirements
- the possibility of handling other sound sources than VSL VIs - audio tracks and VST-Plugins from other manufacturers).
But I know - we live in the age of hurry and convenience - even concerning to music production [;)]